Network Initiated Release Assistance Indication

ABSTRACT

A session management function (SMF) receives a message from a network exposure function (NEF). The message comprises downlink data and a release assistance indicator (RAI). The RAI indicates that transmission of uplink data by a wireless device is expected subsequent to transmission of the downlink data. The RAI indicates a release of a connection associated with the wireless device after the transmission of uplink data. The SMF receives an indication that the uplink data is transmitted. The SMF upon receiving the indication, sends a release message to an access and mobility management function (AMF). The release message indicates release of a non-access stratum message associated with the wireless device. The release message comprises the release assistance indicator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/736,238, filed Sep. 25, 2018, which is hereby incorporated byreference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings.

FIG. 1 is a diagram of an example 5G system architecture as per anaspect of an embodiment of the present disclosure.

FIG. 2 is a diagram of an example 5G System architecture as per anaspect of an embodiment of the present disclosure.

FIG. 3 is a system diagram of an example wireless device and a networknode in a 5G system as per an aspect of an embodiment of the presentdisclosure.

FIG. 4 is a system diagram of an example wireless device as per anaspect of an embodiment of the present disclosure.

FIG. 5A and FIG. 5B depict two registration management state models inUE 100 and AMF 155 as per an aspect of embodiments of the presentdisclosure.

FIG. 6A and FIG. 6B depict two connection management state models in UE100 and AMF 155 as per an aspect of embodiments of the presentdisclosure.

FIG. 7 is diagram for classification and marking traffic as per anaspect of an embodiment of the present disclosure.

FIG. 8 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 9 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 10 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 11 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 12 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 13 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 14 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 15 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 16 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 17 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 18 is an example description as per an aspect of an embodiment ofthe present disclosure.

FIG. 19 is an example description as per an aspect of an embodiment ofthe present disclosure.

FIG. 20 is an example description as per an aspect of an embodiment ofthe present disclosure.

FIG. 21 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 22 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 23 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 24 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 25 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 26 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 27 is an example call flow as per an aspect of an embodiment of thepresent disclosure.

FIG. 28 is an example description as per an aspect of an embodiment ofthe present disclosure.

FIG. 29 is an example description as per an aspect of an embodiment ofthe present disclosure.

FIG. 30 is an example depicting an information element as per an aspectof an embodiment of the present disclosure.

FIG. 31 is an example depicting an information element as per an aspectof an embodiment of the present disclosure.

FIG. 32 is an example depicting an information element as per an aspectof an embodiment of the present disclosure.

FIG. 33 is an example flowchart as per an aspect of an embodiment of thepresent disclosure.

FIG. 34 is an example flowchart as per an aspect of an embodiment of thepresent disclosure.

FIG. 35 is an example flowchart as per an aspect of an embodiment of thepresent disclosure.

FIG. 36 is an example flowchart as per an aspect of an embodiment of thepresent disclosure.

FIG. 37 is a flow diagram as per an aspect of an example embodiment ofthe present disclosure.

DETAILED DESCRIPTION OF EXAMPLES

Example embodiments of the present invention enable implementation ofenhanced features and functionalities in 5G systems. Embodiments of thetechnology disclosed herein may be employed in the technical field of 5Gsystems, 5G Cellular Internet of Things (IoT), Machine TypeCommunication (MTC), and network slicing for communication systems. Moreparticularly, the embodiments of the technology disclosed herein mayrelate to 5G core network and 5G systems for 5G Cellular Internet ofThings (IoT), Machine Type Communication (MTC), and network slicing incommunication systems. Throughout the present disclosure, UE, wirelessdevice, and mobile device are used interchangeably. Throughout thepresent disclosure, CIoT, and MTC are used interchangeably.

The following acronyms are used throughout the present disclosure:

5G 5th generation mobile networks

5GC 5G Core Network

5GS 5G System

5G-AN 5G Access Network

5QI 5G QoS Indicator

AF Application Function

AMF Access and Mobility Management Function

AN Access Network

AS Application Server

CDR Charging Data Record

CCNF Common Control Network Functions

CIoT Cellular IoT

CN Core Network

CP Control Plane

DDN Downlink Data Notification

DL Downlink

DN Data Network

DNN Data Network Name

F-TEID Fully Qualified TEID

FQDN Fully Qualified Domain Name

GPSI Generic Public Subscription Identifier

GTP GPRS Tunneling Protocol

GUTI Globally Unique Temporary Identifier

IMSI International Mobile Subscriber Identity

IoT Internet of Things

LADN Local Area Data Network

LI Lawful Intercept

MEI Mobile Equipment Identifier

MICO Mobile Initiated Connection Only

MME Mobility Management Entity

MO Mobile Originated

MSISDN Mobile Subscriber ISDN

MT Mobile Terminating

MTC Machine Type Communication

N3IWF Non-3GPP InterWorking Function

NAI Network Access Identifier

NAS Non-Access Stratum

NB-IoT Narrow Band IoT

NEF Network Exposure Function

NF Network Function

NGAP Next Generation Application Protocol

NIMF Network IoT Messaging Function

NR New Radio

NRF Network Repository Function

NSI Network Slice Instance

NSSAI Network Slice Selection Assistance Information

NSSF Network Slice Selection Function

OCS Online Charging System

OFCS Offline Charging System

PCF Policy Control Function

PDU Packet/Protocol Data Unit

PEI Permanent Equipment Identifier

PLMN Public Land Mobile Network

RAN Radio Access Network

QFI QoS Flow Identity

RM Registration Management

S1-AP S1 Application Protocol

SBA Service Based Architecture

SEA Security Anchor Function

SCM Security Context Management

SCS Service Capability Server

SMF Session Management Function

SMSF SMS Function

S-NSSAI Single Network Slice Selection Assistance information

SUCI Served User Correlation ID

SUPI Subscriber Permanent Identifier

TEID Tunnel Endpoint Identifier

UE User Equipment

UL Uplink

UL CL Uplink Classifier

UPF User Plane Function

URRP UE Reachability Request Parameter

Example FIG. 1 and FIG. 2 depict a 5G system comprising of accessnetworks and 5G core network. An example 5G access network may comprisean access network connecting to a 5G core network. An access network maycomprise an NG-RAN 105 and/or non-3GPP AN 165. An example 5G corenetwork may connect to one or more 5G access networks 5G-AN and/orNG-RANs. 5G core network may comprise functional elements or networkfunctions as in example FIG. 1 and example FIG. 2 where interfaces maybe employed for communication among the functional elements and/ornetwork elements.

In an example, a network function may be a processing function in anetwork, which may have a functional behavior and/or interfaces. Anetwork function may be implemented either as a network element on adedicated hardware, and/or a network node as depicted in FIG. 3 and FIG.4, or as a software instance running on a dedicated hardware and/orshared hardware, or as a virtualized function instantiated on anappropriate platform.

In an example, access and mobility management function, AMF 155, mayinclude the following functionalities (some of the AMF 155functionalities may be supported in a single instance of an AMF 155):termination of RAN 105 CP interface (N2), termination of NAS (N1), NASciphering and integrity protection, registration management, connectionmanagement, reachability management, mobility management, lawfulintercept (for AMF 155 events and interface to LI system), providetransport for session management, SM messages between UE 100 and SMF160, transparent proxy for routing SM messages, access authentication,access authorization, provide transport for SMS messages between UE 100and SMSF, security anchor function, SEA, interaction with the AUSF 150and the UE 100, receiving the intermediate key established as a resultof the UE 100 authentication process, security context management, SCM,that receives a key from the SEA that it uses to derive access networkspecific keys, and/or the like.

In an example, the AMF 155 may support non-3GPP access networks throughN2 interface with N3IWF 170, NAS signaling with a UE 100 over N3IWF 170,authentication of UEs connected over N3IWF 170, management of mobility,authentication, and separate security context state(s) of a UE 100connected via non-3GPP access 165 or connected via 3GPP access 105 andnon-3GPP access 165 simultaneously, support of a coordinated RM contextvalid over 3GPP access 105 and non 3GPP access 165, support of CMmanagement contexts for the UE 100 for connectivity over non-3GPPaccess, and/or the like.

In an example, an AMF 155 region may comprise one or multiple AMF 155sets. The AMF 155 set may comprise some AMF 155 that serve a given areaand/or network slice(s). In an example, multiple AMF 155 sets may be perAMF 155 region and/or network slice(s). Application identifier may be anidentifier that may be mapped to a specific application trafficdetection rule. Configured NSSAI may be an NSSAI that may be provisionedin a UE 100. DN 115 access identifier (DNAI), for a DNN, may be anidentifier of a user plane access to a DN 115. Initial registration maybe related to a UE 100 registration in RM-DEREGISTERED 500, 520 states.N2AP UE 100 association may be a logical per UE 100 association betweena 5G AN node and an AMF 155. N2AP UE-TNLA-binding may be a bindingbetween a N2AP UE 100 association and a specific transport networklayer, TNL association for a given UE 100.

In an example, session management function, SMF 160, may include one ormore of the following functionalities (one or more of the SMF 160functionalities may be supported in a single instance of a SMF 160):session management (e.g. session establishment, modify and release,including tunnel maintain between UPF 110 and AN 105 node), UE 100 IPaddress allocation & management (including optional authorization),selection and control of UP function(s), configuration of trafficsteering at UPF 110 to route traffic to proper destination, terminationof interfaces towards policy control functions, control part of policyenforcement and QoS, lawful intercept (for SM events and interface to LISystem), termination of SM parts of NAS messages, downlink datanotification, initiation of AN specific SM information, sent via AMF 155over N2 to (R)AN 105, determination of SSC mode of a session, roamingfunctionality, handling local enforcement to apply QoS SLAs (VPLMN),charging data collection and charging interface (VPLMN), lawfulintercept (in VPLMN for SM events and interface to LI System), supportfor interaction with external DN 115 for transport of signaling for PDUsession authorization/authentication by external DN 115, and/or thelike.

In an example, a user plane function, UPF 110, may include one or moreof the following functionalities (some of the UPF 110 functionalitiesmay be supported in a single instance of a UPF 110): anchor point forIntra-/Inter-RAT mobility (when applicable), external PDU session pointof interconnect to DN 115, packet routing & forwarding, packetinspection and user plane part of policy rule enforcement, lawfulintercept (UP collection), traffic usage reporting, uplink classifier tosupport routing traffic flows to a data network, branching point tosupport multi-homed PDU session(s), QoS handling for user plane, uplinktraffic verification (SDF to QoS flow mapping), transport level packetmarking in the uplink and downlink, downlink packet buffering, downlinkdata notification triggering, and/or the like.

In an example, the UE 100 IP address management may include allocationand release of the UE 100 IP address and/or renewal of the allocated IPaddress. The UE 100 may set a requested PDU type during a PDU sessionestablishment procedure based on its IP stack capabilities and/orconfiguration. In an example, the SMF 160 may select PDU type of a PDUsession. In an example, if the SMF 160 receives a request with PDU typeset to IP, the SMF 160 may select PDU type IPv4 or IPv6 based on DNNconfiguration and/or operator policies. In an example, the SMF 160 mayprovide a cause value to the UE 100 to indicate whether the other IPversion is supported on the DNN. In an example, if the SMF 160 receivesa request for PDU type IPv4 or IPv6 and the requested IP version issupported by the DNN the SMF 160 may select the requested PDU type.

In an example embodiment, the 5GC elements and UE 100 may support thefollowing mechanisms: during a PDU session establishment procedure, theSMF 160 may send the IP address to the UE 100 via SM NAS signaling. TheIPv4 address allocation and/or IPv4 parameter configuration via DHCPv4may be employed once PDU session may be established. IPv6 prefixallocation may be supported via IPv6 stateless autoconfiguration, ifIPv6 is supported. In an example, 5GC network elements may support IPv6parameter configuration via stateless DHCPv6.

The 5GC may support the allocation of a static IPv4 address and/or astatic IPv6 prefix based on subscription information in a UDM 140 and/orbased on the configuration on a per-subscriber, per-DNN basis.

User plane function(s) (UPF 110) may handle the user plane path of PDUsessions. A UPF 110 that provides the interface to a data network maysupport functionality of a PDU session anchor.

In an example, a policy control function, PCF 135, may support unifiedpolicy framework to govern network behavior, provide policy rules tocontrol plane function(s) to enforce policy rules, implement a front endto access subscription information relevant for policy decisions in auser data repository (UDR), and/or the like.

A network exposure function, NEF 125, may provide means to securelyexpose the services and capabilities provided by the 3GPP networkfunctions, translate between information exchanged with the AF 145 andinformation exchanged with the internal network functions, receiveinformation from other network functions, and/or the like.

In an example, an network repository function, NRF 130 may supportservice discovery function that may receive NF discovery request from NFinstance, provide information about the discovered NF instances (bediscovered) to the NF instance, and maintain information about availableNF instances and their supported services, and/or the like.

In an example, an NSSF 120 may select a set of network slice instancesserving the UE 100, may determine allowed NSSAI. In an example, the NSSF120 may determine the AMF 155 set to be employed to serve the UE 100,and/or, based on configuration, determine a list of candidate AMF 155(s)155 by querying the NRF 130.

In an example, stored data in a UDR may include at least usersubscription data, including at least subscription identifiers, securitycredentials, access and mobility related subscription data, sessionrelated subscription data, policy data, and/or the like.

In an example, an AUSF 150 may support authentication server function(AUSF 150).

In an example, an application function, AF 145, may interact with the3GPP core network to provide services. In an example, based on operatordeployment, application functions may be trusted by the operator tointeract directly with relevant network functions. Application functionsnot allowed by the operator to access directly the network functions mayuse an external exposure framework (e.g., via the NEF 125) to interactwith relevant network functions.

In an example, control plane interface between the (R)AN 105 and the 5Gcore may support connection of multiple different kinds of AN(s) (e.g.3GPP RAN 105, N3IWF 170 for Un-trusted access 165) to the 5GC via acontrol plane protocol. In an example, an N2 AP protocol may be employedfor both the 3GPP access 105 and non-3GPP access 165. In an example,control plane interface between the (R)AN 105 and the 5G core maysupport decoupling between AMF 155 and other functions such as SMF 160that may need to control the services supported by AN(s) (e.g. controlof the UP resources in the AN 105 for a PDU session).

In an example, the 5GC may provide policy information from the PCF 135to the UE 100. In an example, the policy information may comprise:access network discovery and selection policy, UE 100 route selectionpolicy (URSP), SSC mode selection policy (SSCMSP), network sliceselection policy (NSSP), DNN selection policy, non-seamless offloadpolicy, and/or the like.

In an example, as depicted in example FIG. 5A and FIG. 5B, theregistration management, RM may be employed to register or de-register aUE/user 100 with the network, and establish the user context in thenetwork. Connection management may be employed to establish and releasethe signaling connection between the UE 100 and the AMF 155.

In an example, a UE 100 may register with the network to receiveservices that require registration. In an example, the UE 100 may updateits registration with the network periodically in order to remainreachable (periodic registration update), or upon mobility (e.g.,mobility registration update), or to update its capabilities or tore-negotiate protocol parameters.

In an example, an initial registration procedure as depicted in exampleFIG. 8 and FIG. 9 may involve execution of network access controlfunctions (e.g. user authentication and access authorization based onsubscription profiles in UDM 140). Example FIG. 9 is a continuation ofthe initial registration procedure depicted in FIG. 8. As a result ofthe initial registration procedure, the identity of the serving AMF 155may be registered in a UDM 140.

In an example, the registration management, RM procedures may beapplicable over both 3GPP access 105 and non 3GPP access 165.

An example FIG. 5A may depict the RM states of a UE 100 as observed bythe UE 100 and AMF 155. In an example embodiment, two RM states may beemployed in the UE 100 and the AMF 155 that may reflect the registrationstatus of the UE 100 in the selected PLMN: RM-DEREGISTERED 500, andRM-REGISTERED 510. In an example, in the RM DEREGISTERED state 500, theUE 100 may not be registered with the network. The UE 100 context in theAMF 155 may not hold valid location or routing information for the UE100 so the UE 100 may not be reachable by the AMF 155. In an example,the UE 100 context may be stored in the UE 100 and the AMF 155. In anexample, in the RM REGISTERED state 510, the UE 100 may be registeredwith the network. In the RM-REGISTERED 510 state, the UE 100 may receiveservices that may require registration with the network.

In an example embodiment, two RM states may be employed in AMF 155 forthe UE 100 that may reflect the registration status of the UE 100 in theselected PLMN: RM-DEREGISTERED 520, and RM-REGISTERED 530.

As depicted in example FIG. 6A and FIG. 6B, connection management, CM,may comprise establishing and releasing a signaling connection between aUE 100 and an AMF 155 over N1 interface. The signaling connection may beemployed to enable NAS signaling exchange between the UE 100 and thecore network. The signaling connection between the UE 100 and the AMF155 may comprise both the AN signaling connection between the UE 100 andthe (R)AN 105 (e.g. RRC connection over 3GPP access) and the N2connection for the UE 100 between the AN and the AMF 155.

As depicted in example FIG. 6A and FIG. 6B, two CM states may beemployed for the NAS signaling connectivity of the UE 100 with the AMF155, CM-IDLE 600, 620 and CM-CONNECTED 610, 630. A UE 100 in CM-IDLE 600state may be in RM-REGISTERED 510 state and may have no NAS signalingconnection established with the AMF 155 over N1. The UE 100 may performcell selection, cell reselection, PLMN selection, and/or the like. A UE100 in CM-CONNECTED 610 state may have a NAS signaling connection withthe AMF 155 over N1.

In an example embodiment two CM states may be employed for the UE 100 atthe AMF 155, CM-IDLE 620 and CM-CONNECTED 630.

In an example, an RRC inactive state may apply to NG-RAN (e.g. it mayapply to NR and E-UTRA connected to 5G CN). The AMF 155, based onnetwork configuration, may provide assistance information to the NG RAN105, to assist the NG RAN's 105 decision whether the UE 100 may be sentto RRC inactive state. When a UE 100 is CM-CONNECTED 610 with RRCinactive state, the UE 100 may resume the RRC connection due to uplinkdata pending, mobile initiated signaling procedure, as a response to RAN105 paging, to notify the network that it has left the RAN 105notification area, and/or the like.

In an example, a NAS signaling connection management may includeestablishing and releasing a NAS signaling connection. A NAS signalingconnection establishment function may be provided by the UE 100 and theAMF 155 to establish the NAS signaling connection for the UE 100 inCM-IDLE 600 state. The procedure of releasing the NAS signalingconnection may be initiated by the 5G (R)AN 105 node or the AMF 155.

In an example, reachability management of a UE 100 may detect whetherthe UE 100 is reachable and may provide the UE 100 location (e.g. accessnode) to the network to reach the UE 100. Reachability management may bedone by paging the UE 100 and the UE 100 location tracking. The UE 100location tracking may include both UE 100 registration area tracking andUE 100 reachability tracking. The UE 100 and the AMF 155 may negotiateUE 100 reachability characteristics in CM-IDLE 600, 620 state duringregistration and registration update procedures.

In an example, two UE 100 reachability categories may be negotiatedbetween a UE 100 and an AMF 155 for CM-IDLE 600, 620 state. 1) UE 100reachability allowing mobile device terminated data while the UE 100 isCM-IDLE 600 mode. 2) Mobile initiated connection only (MICO) mode. The5GC may support a PDU connectivity service that provides exchange ofPDUs between the UE 100 and a data network identified by a DNN. The PDUconnectivity service may be supported via PDU sessions that areestablished upon request from the UE 100.

In an example, a PDU session may support one or more PDU session types.PDU sessions may be established (e.g. upon UE 100 request), modified(e.g. upon UE 100 and 5GC request) and/or released (e.g. upon UE 100 and5GC request) using NAS SM signaling exchanged over N1 between the UE 100and the SMF 160. Upon request from an application server, the 5GC may beable to trigger a specific application in the UE 100. When receiving thetrigger, the UE 100 may send it to the identified application in the UE100. The identified application in the UE 100 may establish a PDUsession to a specific DNN.

In an example, the 5G QoS model may support a QoS flow based frameworkas depicted in example FIG. 7. The 5G QoS model may support both QoSflows that require a guaranteed flow bit rate and QoS flows that may notrequire a guaranteed flow bit rate. In an example, the 5G QoS model maysupport reflective QoS. The QoS model may comprise flow mapping orpacket marking at the UPF 110 (CN_UP) 110, AN 105 and/or the UE 100. Inan example, packets may arrive from and/or destined to theapplication/service layer 730 of UE 100, UPF 110 (CN_UP) 110, and/or theAF 145.

In an example, the QoS flow may be a granularity of QoS differentiationin a PDU session. A QoS flow ID, QFI, may be employed to identify theQoS flow in the 5G system. In an example, user plane traffic with thesame QFI within a PDU session may receive the same traffic forwardingtreatment. The QFI may be carried in an encapsulation header on N3and/or N9 (e.g. without any changes to the end-to-end packet header). Inan example, the QFI may be applied to PDUs with different types ofpayload. The QFI may be unique within a PDU session.

In an example, the QoS parameters of a QoS flow may be provided to the(R)AN 105 as a QoS profile over N2 at PDU session establishment, QoSflow establishment, or when NG-RAN is used at every time the user planeis activated. In an example, a default QoS rule may be required forevery PDU session. The SMF 160 may allocate the QFI for a QoS flow andmay derive QoS parameters from the information provided by the PCF 135.In an example, the SMF 160 may provide the QFI together with the QoSprofile containing the QoS parameters of a QoS flow to the (R)AN 105.

In an example, 5G QoS flow may be a granularity for QoS forwardingtreatment in the 5G system. Traffic mapped to the same 5G QoS flow mayreceive the same forwarding treatment (e.g. scheduling policy, queuemanagement policy, rate shaping policy, RLC configuration, and/or thelike). In an example, providing different QoS forwarding treatment mayrequire separate 5G QoS flows.

In an example, a 5G QoS indicator may be a scalar that may be employedas a reference to a specific QoS forwarding behavior (e.g. packet lossrate, packet delay budget) to be provided to a 5G QoS flow. In anexample, the 5G QoS indicator may be implemented in the access networkby the 5QI referencing node specific parameters that may control the QoSforwarding treatment (e.g. scheduling weights, admission thresholds,queue management thresholds, link layer protocol configuration, and/orthe like.).

In an example, 5GC may support edge computing and may enable operator(s)and 3rd party services to be hosted close to the UE's access point ofattachment. The 5G core network may select a UPF 110 close to the UE 100and may execute the traffic steering from the UPF 110 to the local datanetwork via a N6 interface. In an example, the selection and trafficsteering may be based on the UE's 100 subscription data, UE 100location, the information from application function AF 145, policy,other related traffic rules, and/or the like. In an example, the 5G corenetwork may expose network information and capabilities to an edgecomputing application function. The functionality support for edgecomputing may include local routing where the 5G core network may selecta UPF 110 to route the user traffic to the local data network, trafficsteering where the 5G core network may select the traffic to be routedto the applications in the local data network, session and servicecontinuity to enable UE 100 and application mobility, user planeselection and reselection, e.g. based on input from applicationfunction, network capability exposure where 5G core network andapplication function may provide information to each other via NEF 125,QoS and charging where PCF 135 may provide rules for QoS control andcharging for the traffic routed to the local data network, support oflocal area data network where 5G core network may provide support toconnect to the LADN in a certain area where the applications aredeployed, and/or the like.

An example 5G system may be a 3GPP system comprising of 5G accessnetwork 105, 5G core network and a UE 100, and/or the like. AllowedNSSAI may be an NSSAI provided by a serving PLMN during e.g. aregistration procedure, indicating the NSSAI allowed by the network forthe UE 100 in the serving PLMN for the current registration area.

In an example, a PDU connectivity service may provide exchange of PDUsbetween a UE 100 and a data network. A PDU session may be an associationbetween the UE 100 and the data network, DN 115, that may provide thePDU connectivity service. The type of association may be IP, Ethernetand/or unstructured.

Establishment of user plane connectivity to a data network via networkslice instance(s) may comprise the following: performing a RM procedureto select an AMF 155 that supports the required network slices, andestablishing one or more PDU session(s) to the required data network viathe network slice instance(s).

In an example, the set of network slices for a UE 100 may be changed atany time while the UE 100 may be registered with the network, and may beinitiated by the network, or the UE 100.

In an example, a periodic registration update may be UE 100re-registration at expiry of a periodic registration timer. A requestedNSSAI may be a NSSAI that the UE 100 may provide to the network.

In an example, a service based interface may represent how a set ofservices may be provided/exposed by a given NF.

In an example, a service continuity may be an uninterrupted userexperience of a service, including the cases where the IP address and/oranchoring point may change. In an example, a session continuity mayrefer to continuity of a PDU session. For PDU session of IP type sessioncontinuity may imply that the IP address is preserved for the lifetimeof the PDU session. An uplink classifier may be a UPF 110 functionalitythat aims at diverting uplink traffic, based on filter rules provided bythe SMF 160, towards data network, DN 115.

In an example, the 5G system architecture may support data connectivityand services enabling deployments to use techniques such as e.g. networkfunction virtualization and/or software defined networking. The 5Gsystem architecture may leverage service-based interactions betweencontrol plane (CP) network functions where identified. In 5G systemarchitecture, separation of the user plane (UP) functions from thecontrol plane functions may be considered. A 5G system may enable anetwork function to interact with other NF(s) directly if required.

In an example, the 5G system may reduce dependencies between the accessnetwork (AN) and the core network (CN). The architecture may comprise aconverged access-agnostic core network with a common AN-CN interfacewhich may integrate different 3GPP and non-3GPP access types.

In an example, the 5G system may support a unified authenticationframework, stateless NFs, where the compute resource is decoupled fromthe storage resource, capability exposure, and concurrent access tolocal and centralized services. To support low latency services andaccess to local data networks, UP functions may be deployed close to theaccess network.

In an example, the 5G system may support roaming with home routedtraffic and/or local breakout traffic in the visited PLMN. An example 5Garchitecture may be service-based and the interaction between networkfunctions may be represented in two ways. (1) As service-basedrepresentation (depicted in example FIG. 1), where network functionswithin the control plane, may enable other authorized network functionsto access their services. This representation may also includepoint-to-point reference points where necessary. (2) Reference pointrepresentation, showing the interaction between the NF services in thenetwork functions described by point-to-point reference point (e.g. N11)between any two network functions.

In an example, a network slice may comprise the core network controlplane and user plane network functions, the 5G Radio Access Network; theN3IWF functions to the non-3GPP Access Network, and/or the like. Networkslices may differ for supported features and network functionimplementation. The operator may deploy multiple network slice instancesdelivering the same features but for different groups of UEs, e.g. asthey deliver a different committed service and/or because they may bededicated to a customer. The NSSF 120 may store the mapping informationbetween slice instance ID and NF ID (or NF address).

In an example, a UE 100 may simultaneously be served by one or morenetwork slice instances via a 5G-AN. In an example, the UE 100 may beserved by k network slices (e.g. k=8, 16, etc.) at a time. An AMF 155instance serving the UE 100 logically may belong to a network sliceinstance serving the UE 100.

In an example, a PDU session may belong to one specific network sliceinstance per PLMN. In an example, different network slice instances maynot share a PDU session. Different slices may have slice-specific PDUsessions using the same DNN.

An S-NSSAI (Single Network Slice Selection Assistance information) mayidentify a network slice. An S-NSSAI may comprise a slice/service type(SST), which may refer to the expected network slice behavior in termsof features and services; and/or a slice differentiator (SD). A slicedifferentiator may be optional information that may complement theslice/service type(s) to allow further differentiation for selecting anetwork slice instance from potentially multiple network slice instancesthat comply with the indicated slice/service type. In an example, thesame network slice instance may be selected employing differentS-NSSAIs. The CN part of a network slice instance(s) serving a UE 100may be selected by CN.

In an example, subscription data may include the S-NSSAI(s) of thenetwork slices that the UE 100 subscribes to. One or more S-NSSAIs maybe marked as default S-NSSAI. In an example, k S-NSSAI may be markeddefault S-NSSAI (e.g. k=8, 16, etc.). In an example, the UE 100 maysubscribe to more than 8 S-NSSAIs.

In an example, a UE 100 may be configured by the HPLMN with a configuredNSSAI per PLMN. Upon successful completion of a UE's registrationprocedure, the UE 100 may obtain from the AMF 155 an Allowed NSSAI forthis PLMN, which may include one or more S-NSSAIs.

In an example, the Allowed NSSAI may take precedence over the configuredNSSAI for a PLMN. The UE 100 may use the S-NSSAIs in the allowed NSSAIcorresponding to a network slice for the subsequent network sliceselection related procedures in the serving PLMN.

In an example, the establishment of user plane connectivity to a datanetwork via a network slice instance(s) may comprise: performing a RMprocedure to select an AMF 155 that may support the required networkslices, establishing one or more PDU sessions to the required datanetwork via the network slice instance(s), and/or the like.

In an example, when a UE 100 registers with a PLMN, if the UE 100 forthe PLMN has a configured NSSAI or an allowed NSSAI, the UE 100 mayprovide to the network in RRC and NAS layer a requested NSSAI comprisingthe S-NSSAI(s) corresponding to the slice(s) to which the UE 100attempts to register, a temporary user ID if one was assigned to the UE,and/or the like. The requested NSSAI may be configured-NSSAI,allowed-NSSAI, and/or the like.

In an example, when a UE 100 registers with a PLMN, if for the PLMN theUE 100 has no configured NSSAI or allowed NSSAI, the RAN 105 may routeNAS signaling from/to the UE 100 to/from a default AMF 155.

In an example, the network, based on local policies, subscriptionchanges and/or UE 100 mobility, may change the set of permitted networkslice(s) to which the UE 100 is registered. In an example, the networkmay perform the change during a registration procedure or trigger anotification towards the UE 100 of the change of the supported networkslices using an RM procedure (which may trigger a registrationprocedure). The network may provide the UE 100 with a new allowed NSSAIand tracking area list.

In an example, during a registration procedure in a PLMN, in case thenetwork decides that the UE 100 should be served by a different AMF 155based on network slice(s) aspects, the AMF 155 that first received theregistration request may redirect the registration request to anotherAMF 155 via the RAN 105 or via direct signaling between the initial AMF155 and the target AMF 155.

In an example, the network operator may provision the UE 100 withnetwork slice selection policy (NSSP). The NSSP may comprise one or moreNSSP rules.

In an example, if a UE 100 has one or more PDU sessions establishedcorresponding to a specific S-NSSAI, the UE 100 may route the user dataof the application in one of the PDU sessions, unless other conditionsin the UE 100 may prohibit the use of the PDU sessions. If theapplication provides a DNN, then the UE 100 may consider the DNN todetermine which PDU session to use. In an example, if the UE 100 doesnot have a PDU session established with the specific S-NSSAI, the UE 100may request a new PDU session corresponding to the S-NSSAI and with theDNN that may be provided by the application. In an example, in order forthe RAN 105 to select a proper resource for supporting network slicingin the RAN 105, the RAN 105 may be aware of the network slices used bythe UE 100.

In an example, an AMF 155 may select an SMF 160 in a network sliceinstance based on S-NSSAI, DNN and/or other information e.g. UE 100subscription and local operator policies, and/or the like, when the UE100 triggers the establishment of a PDU session. The selected SMF 160may establish the PDU session based on S-NSSAI and DNN.

In an example, in order to support network-controlled privacy of sliceinformation for the slices the UE 100 may access, when the UE 100 isaware or configured that privacy considerations may apply to NSSAI, theUE 100 may not include NSSAI in NAS signaling unless the UE 100 has aNAS security context and the UE 100 may not include NSSAI in unprotectedRRC signaling.

In an example, for roaming scenarios, the network slice specific networkfunctions in VPLMN and HPLMN may be selected based on the S-NSSAIprovided by the UE 100 during PDU connection establishment. If astandardized S-NSSAI is used, selection of slice specific NF instancesmay be done by one or more PLMNs based on the provided S-NSSAI. In anexample, the VPLMN may map the S-NSSAI of HPLMN to a S-NSSAI of VPLMNbased on roaming agreement (e.g., including mapping to a default S-NSSAIof VPLMN). In an example, the selection of slice specific NF instance inVPLMN may be done based on the S-NSSAI of VPLMN. In an example, theselection of any slice specific NF instance in HPLMN may be based on theS-NSSAI of HPLMN.

As depicted in example FIG. 8 and FIG. 9, a registration procedure maybe performed by the UE 100 to get authorized to receive services, toenable mobility tracking, to enable reachability, and/or the like.

In an example, the UE 100 may send to the (R)AN 105 an AN message(comprising AN parameters, RM-NAS registration request (registrationtype, SUCI or SUPI or 5G-GUTI, last visited TAI (if available), securityparameters, requested NSSAI, mapping of requested NSSAI, UE 100 5GCcapability, PDU session status, PDU session(s) to be re-activated,Follow on request, MICO mode preference, and/or the like), and/or thelike). In an example, in case of NG-RAN, the AN parameters may includee.g. SUCI or SUPI or the 5G-GUTI, the Selected PLMN ID and requestedNSSAI, and/or the like. In an example, the AN parameters may compriseestablishment cause. The establishment cause may provide the reason forrequesting the establishment of an RRC connection. In an example, theregistration type may indicate if the UE 100 wants to perform an initialregistration (i.e. the UE 100 is in RM-DEREGISTERED state), a mobilityregistration update (e.g., the UE 100 is in RM-REGISTERED state andinitiates a registration procedure due to mobility), a periodicregistration update (e.g., the UE 100 is in RM-REGISTERED state and mayinitiate a registration procedure due to the periodic registrationupdate timer expiry) or an emergency registration (e.g., the UE 100 isin limited service state). In an example, if the UE 100 performing aninitial registration (i.e., the UE 100 is in RM-DEREGISTERED state) to aPLMN for which the UE 100 does not already have a 5G-GUTI, the UE 100may include its SUCI or SUPI in the registration request. The SUCI maybe included if the home network has provisioned the public key toprotect SUPI in the UE. If the UE 100 received a UE 100 configurationupdate command indicating that the UE 100 needs to re-register and the5G-GUTI is invalid, the UE 100 may perform an initial registration andmay include the SUPI in the registration request message. For anemergency registration, the SUPI may be included if the UE 100 does nothave a valid 5G-GUTI available; the PEI may be included when the UE 100has no SUPI and no valid 5G-GUTI. In other cases, the 5G-GUTI may beincluded and it may indicate the last serving AMF 155. If the UE 100 isalready registered via a non-3GPP access in a PLMN different from thenew PLMN (e.g., not the registered PLMN or an equivalent PLMN of theregistered PLMN) of the 3GPP access, the UE 100 may not provide over the3GPP access the 5G-GUTI allocated by the AMF 155 during the registrationprocedure over the non-3GPP access. If the UE 100 is already registeredvia a 3GPP access in a PLMN (e.g., the registered PLMN), different fromthe new PLMN (i.e. not the registered PLMN or an equivalent PLMN of theregistered PLMN) of the non-3GPP access, the UE 100 may not provide overthe non-3GPP access the 5G-GUTI allocated by the AMF 155 during theregistration procedure over the 3GPP access. The UE 100 may provide theUE's usage setting based on its configuration. In case of initialregistration or mobility registration update, the UE 100 may include themapping of requested NSSAI, which may be the mapping of one or moreS-NSSAIs of the requested NSSAI to the S-NSSAIs of the configured NSSAIfor the HPLMN, to ensure that the network is able to verify whether theS-NSSAI(s) in the requested NSSAI are permitted based on the subscribedS-NSSAIs. If available, the last visited TAI may be included in order tohelp the AMF 155 produce registration area for the UE. In an example,the security parameters may be used for authentication and integrityprotection. requested NSSAI may indicate the network slice selectionassistance information. The PDU session status may indicates thepreviously established PDU sessions in the UE. When the UE 100 isconnected to the two AMF 155 belonging to different PLMN via 3GPP accessand non-3GPP access then the PDU session status may indicate theestablished PDU session of the current PLMN in the UE. The PDUsession(s) to be re-activated may be included to indicate the PDUsession(s) for which the UE 100 may intend to activate UP connections. APDU session corresponding to a LADN may not be included in the PDUsession(s) to be re-activated when the UE 100 is outside the area ofavailability of the LADN. The follow on request may be included when theUE 100 may have pending uplink signaling and the UE 100 may not includePDU session(s) to be re-activated, or the registration type may indicatethe UE 100 may want to perform an emergency registration.

In an example, if a SUPI is included or the 5G-GUTI does not indicate avalid AMF 155, the (R)AN 105, based on (R)AT and requested NSSAI, ifavailable, may select 808 an AMF 155. If UE 100 is in CM-CONNECTEDstate, the (R)AN 105 may forward the registration request message to theAMF 155 based on the N2 connection of the UE. If the (R)AN 105 may notselect an appropriate AMF 155, it may forward the registration requestto an AMF 155 which has been configured, in (R)AN 105, to perform AMF155 selection 808.

In an example, the (R)AN 105 may send to the new AMF 155 an N2 message(comprising: N2 parameters, RM-NAS registration request (registrationtype, SUPI or 5G-GUTI, last visited TAI (if available), securityparameters, requested NSSAI, mapping of requested NSSAI, UE 100 5GCcapability, PDU session status, PDU session(s) to be re-activated,follow on request, and MICO mode preference), and/or the like). In anexample, when NG-RAN is used, the N2 parameters may comprise theselected PLMN ID, location information, cell identity and the RAT typerelated to the cell in which the UE 100 is camping. In an example, whenNG-RAN is used, the N2 parameters may include the establishment cause.

In an example, the new AMF 155 may send to the old AMF 155 anNamf_Communication_UEContextTransfer (complete registration request). Inan example, if the UE's 5G-GUTI was included in the registration requestand the serving AMF 155 has changed since last registration procedure,the new AMF 155 may invoke the Namf_Communication_UEContextTransferservice operation on the old AMF 155 including the complete registrationrequest IE, which may be integrity protected, to request the UE's SUPIand MM Context. The old AMF 155 may use the integrity protected completeregistration request IE to verify if the context transfer serviceoperation invocation corresponds to the UE 100 requested. In an example,the old AMF 155 may transfer the event subscriptions information by oneor more NF consumers, for the UE, to the new AMF 155. In an example, ifthe UE 100 identifies itself with PEI, the SUPI request may be skipped.

In an example, the old AMF 155 may send to new AMF 155 a response toNamf_Communication_UEContextTransfer (SUPI, MM context, SMF 160information, PCF ID). In an example, the old AMF 155 may respond to thenew AMF 155 for the Namf_Communication_UEContextTransfer invocation byincluding the UE's SUPI and MM context. In an example, if old AMF 155holds information about established PDU sessions, the old AMF 155 mayinclude SMF 160 information including S-NSSAI(s), SMF 160 identities andPDU session ID. In an example, if old AMF 155 holds information aboutactive NGAP UE-TNLA bindings to N3IWF, the old AMF 155 may includeinformation about the NGAP UE-TNLA bindings.

In an example, if the SUPI is not provided by the UE 100 nor retrievedfrom the old AMF 155 the identity request procedure may be initiated bythe AMF 155 sending an identity request message to the UE 100 requestingthe SUCI.

In an example, the UE 100 may respond with an identity response messageincluding the SUCI. The UE 100 may derive the SUCI by using theprovisioned public key of the HPLMN.

In an example, the AMF 155 may decide to initiate UE 100 authentication825 by invoking an AUSF 150. The AMF 155 may select an AUSF 150 based onSUPI or SUCI. In an example, if the AMF 155 is configured to supportemergency registration for unauthenticated SUPIs and the UE 100indicated registration type emergency registration the AMF 155 may skipthe authentication and security setup or the AMF 155 may accept that theauthentication may fail and may continue the registration procedure.

In an example, the authentication 830 may be performed byNudm_UEAuthenticate_Get operation. The AUSF 150 may discover a UDM 140.In case the AMF 155 provided a SUCI to AUSF 150, the AUSF 150 may returnthe SUPI to AMF 155 after the authentication is successful. In anexample, if network slicing is used, the AMF 155 may decide if theregistration request needs to be rerouted where the initial AMF 155refers to the AMF 155. In an example, the AMF 155 may initiate NASsecurity functions. In an example, upon completion of NAS securityfunction setup, the AMF 155 may initiate NGAP procedure to enable 5G-ANuse it for securing procedures with the UE. In an example, the 5G-AN maystore the security context and may acknowledge to the AMF 155. The 5G-ANmay use the security context to protect the messages exchanged with theUE.

In an example, new AMF 155 may send to the old AMF 155Namf_Communication_RegistrationCompleteNotify. If the AMF 155 haschanged, the new AMF 155 may notify the old AMF 155 that theregistration of the UE 100 in the new AMF 155 may be completed byinvoking the Namf_Communication_RegistrationCompleteNotify serviceoperation. If the authentication/security procedure fails, then theregistration may be rejected, and the new AMF 155 may invoke theNamf_Communication_RegistrationCompleteNotify service operation with areject indication reason code towards the old AMF 155. The old AMF 155may continue as if the UE 100 context transfer service operation wasnever received. If one or more of the S-NSSAIs used in the oldregistration area may not be served in the target registration area, thenew AMF 155 may determine which PDU session may not be supported in thenew registration area. The new AMF 155 may invoke theNamf_Communication_RegistrationCompleteNotify service operationincluding the rejected PDU session ID and a reject cause (e.g. theS-NSSAI becomes no longer available) towards the old AMF 155. The newAMF 155 may modify the PDU session status correspondingly. The old AMF155 may inform the corresponding SMF 160(s) to locally release the UE'sSM context by invoking the Nsmf_PDUSession_ReleaseSMContext serviceoperation.

In an example, the new AMF 155 may send to the UE 100 an identityrequest/response (e.g., PEI). If the PEI was not provided by the UE 100nor retrieved from the old AMF 155, the identity request procedure maybe initiated by AMF 155 sending an identity request message to the UE100 to retrieve the PEI. The PEI may be transferred encrypted unless theUE 100 performs emergency registration and may not be authenticated. Foran emergency registration, the UE 100 may have included the PEI in theregistration request.

In an example, the new AMF 155 may initiate ME identity check byinvoking the N5g-eir_EquipmentldentityCheck_Get service operation.

In an example, the new AMF 155, based on the SUPI, may select 905 a UDM140. The UDM 140 may select a UDR instance. In an example, the AMF 155may select a UDM 140.

In an example, if the AMF 155 has changed since the last registrationprocedure, or if the UE 100 provides a SUPI which may not refer to avalid context in the AMF 155, or if the UE 100 registers to the same AMF155 it has already registered to a non-3GPP access (e.g., the UE 100 isregistered over a non-3GPP access and may initiate the registrationprocedure to add a 3GPP access), the new AMF 155 may register with theUDM 140 using Nudm_UECM_Registration and may subscribe to be notifiedwhen the UDM 140 may deregister the AMF 155. The UDM 140 may store theAMF 155 identity associated to the access type and may not remove theAMF 155 identity associated to the other access type. The UDM 140 maystore information provided at registration in UDR, by Nudr_UDM_Update.In an example, the AMF 155 may retrieve the access and mobilitysubscription data and SMF 160 selection subscription data usingNudm_SDM_Get. The UDM 140 may retrieve this information from UDR byNudr_UDM_Query(access and mobility subscription data). After asuccessful response is received, the AMF 155 may subscribe to benotified using Nudm_SDM_Subscribe when the data requested may bemodified. The UDM 140 may subscribe to UDR by Nudr_UDM_Subscribe. TheGPSI may be provided to the AMF 155 in the subscription data from theUDM 140 if the GPSI is available in the UE 100 subscription data. In anexample, the new AMF 155 may provide the access type it serves for theUE 100 to the UDM 140 and the access type may be set to 3GPP access. TheUDM 140 may store the associated access type together with the servingAMF 155 in UDR by Nudr_UDM_Update. The new AMF 155 may create an MMcontext for the UE 100 after getting the mobility subscription data fromthe UDM 140. In an example, when the UDM 140 stores the associatedaccess type together with the serving AMF 155, the UDM 140 may initiatea Nudm_UECM_DeregistrationNotification to the old AMF 155 correspondingto 3GPP access. The old AMF 155 may remove the MM context of the UE. Ifthe serving NF removal reason indicated by the UDM 140 is initialregistration, then the old AMF 155 may invoke theNamf_EventExposure_Notify service operation towards the associated SMF160 s of the UE 100 to notify that the UE 100 is deregistered from oldAMF 155. The SMF 160 may release the PDU session(s) on getting thisnotification. In an example, the old AMF 155 may unsubscribe with theUDM 140 for subscription data using Nudm_SDM_unsubscribe.

In an example, if the AMF 155 decides to initiate PCF 135 communication,e.g. the AMF 155 has not yet obtained access and mobility policy for theUE 100 or if the access and mobility policy in the AMF 155 are no longervalid, the AMF 155 may select 925 a PCF 135. If the new AMF 155 receivesa PCF ID from the old AMF 155 and successfully contacts the PCF 135identified by the PCF ID, the AMF 155 may select the (V-)PCF identifiedby the PCF ID. If the PCF 135 identified by the PCF ID may not be used(e.g. no response from the PCF 135) or if there is no PCF ID receivedfrom the old AMF 155, the AMF 155 may select 925 a PCF 135.

In an example, the new AMF 155 may perform a policy associationestablishment during registration procedure. If the new AMF 155 contactsthe PCF 135 identified by the (V-) PCF ID received during inter-AMF 155mobility, the new AMF 155 may include the PCF-ID in theNpcf_AMPolicyControl Get operation. If the AMF 155 notifies the mobilityrestrictions (e.g. UE 100 location) to the PCF 135 for adjustment, or ifthe PCF 135 updates the mobility restrictions itself due to someconditions (e.g. application in use, time and date), the PCF 135 mayprovide the updated mobility restrictions to the AMF 155.

In an example, the PCF 135 may invoke Namf_EventExposure_Subscribeservice operation for UE 100 event subscription.

In an example, the AMF 155 may send to the SMF 160 anNsmf_PDUSession_UpdateSMContext. In an example, the AMF 155 may invokethe Nsmf_PDUSession_UpdateSMContext if the PDU session(s) to bere-activated is included in the registration request. The AMF 155 maysend Nsmf_PDUSession_UpdateSMContext request to SMF 160(s) associatedwith the PDU session(s) to activate user plane connections of the PDUsession(s). The SMF 160 may decide to trigger e.g. the intermediate UPF110 insertion, removal or change of PSA. In the case that theintermediate UPF 110 insertion, removal, or relocation is performed forthe PDU session(s) not included in PDU session(s) to be re-activated,the procedure may be performed without N11 and N2 interactions to updatethe N3 user plane between (R)AN 105 and 5GC. The AMF 155 may invoke theNsmf_PDUSession_ReleaseSMContext service operation towards the SMF 160if any PDU session status indicates that it is released at the UE 100.The AMF 155 may invoke the Nsmf_PDUSession_ReleaseSMContext serviceoperation towards the SMF 160 in order to release any network resourcesrelated to the PDU session.

In an example, the new AMF 155155 may send to a N3IWF an N2 AMF 155mobility request. If the AMF 155 has changed, the new AMF 155 may createan NGAP UE 100 association towards the N3IWF to which the UE 100 isconnected. In an example, the N3IWF may respond to the new AMF 155 withan N2 AMF 155 mobility response.

In an example, the new AMF 155 may send to the UE 100 a registrationaccept (comprising: 5G-GUTI, registration area, mobility restrictions,PDU session status, allowed NSSAI, [mapping of allowed NSSAI], periodicregistration update timer, LADN information and accepted MICO mode, IMSvoice over PS session supported indication, emergency service supportindicator, and/or the like). In an example, the AMF 155 may send theregistration accept message to the UE 100 indicating that theregistration request has been accepted. 5G-GUTI may be included if theAMF 155 allocates a new 5G-GUTI. If the AMF 155 allocates a newregistration area, it may send the registration area to the UE 100 viaregistration accept message. If there is no registration area includedin the registration accept message, the UE 100 may consider the oldregistration area as valid. In an example, mobility restrictions may beincluded in case mobility restrictions may apply for the UE 100 andregistration type may not be emergency registration. The AMF 155 mayindicate the established PDU sessions to the UE 100 in the PDU sessionstatus. The UE 100 may remove locally any internal resources related toPDU sessions that are not marked as established in the received PDUsession status. In an example, when the UE 100 is connected to the twoAMF 155 belonging to different PLMN via 3GPP access and non-3GPP accessthen the UE 100 may remove locally any internal resources related to thePDU session of the current PLMN that are not marked as established inreceived PDU session status. If the PDU session status information wasin the registration request, the AMF 155 may indicate the PDU sessionstatus to the UE. The mapping of allowed NSSAI may be the mapping of oneor more S-NSSAI of the allowed NSSAI to the S-NSSAIs of the configuredNSSAI for the HPLMN. The AMF 155 may include in the registration acceptmessage the LADN information for LADNs that are available within theregistration area determined by the AMF 155 for the UE. If the UE 100included MICO mode in the request, then AMF 155 may respond whether MICOmode may be used. The AMF 155 may set the IMS voice over PS sessionsupported Indication. In an example, in order to set the IMS voice overPS session supported indication, the AMF 155 may perform a UE/RAN radioinformation and compatibility request procedure to check thecompatibility of the UE 100 and RAN radio capabilities related to IMSvoice over PS. In an example, the emergency service support indicatormay inform the UE 100 that emergency services are supported, e.g., theUE 100 may request PDU session for emergency services. In an example,the handover restriction list and UE-AMBR may be provided to NG-RAN bythe AMF 155.

In an example, the UE 100 may send to the new AMF 155 a registrationcomplete message. In an example, the UE 100 may send the registrationcomplete message to the AMF 155 to acknowledge that a new 5G-GUTI may beassigned. In an example, when information about the PDU session(s) to bere-activated is not included in the registration request, the AMF 155may release the signaling connection with the UE 100. In an example,when the follow-on request is included in the registration request, theAMF 155 may not release the signaling connection after the completion ofthe registration procedure. In an example, if the AMF 155 is aware thatsome signaling is pending in the AMF 155 or between the UE 100 and theSGC, the AMF 155 may not release the signaling connection after thecompletion of the registration procedure.

As depicted in example FIG. 10 and FIG. 11, a service request proceduree.g., a UE 100 triggered service request procedure may be used by a UE100 in CM-IDLE state to request the establishment of a secure connectionto an AMF 155. FIG. 11 is continuation of FIG. 10 depicting the servicerequest procedure. The service request procedure may be used to activatea user plane connection for an established PDU session. The servicerequest procedure may be triggered by the UE 100 or the SGC, and may beused when the UE 100 is in CM-IDLE and/or in CM-CONNECTED and may allowselectively to activate user plane connections for some of theestablished PDU sessions.

In an example, a UE 100 in CM IDLE state may initiate the servicerequest procedure to send uplink signaling messages, user data, and/orthe like, as a response to a network paging request, and/or the like. Inan example, after receiving the service request message, the AMF 155 mayperform authentication. In an example, after the establishment ofsignaling connection to the AMF 155, the UE 100 or network may sendsignaling messages, e.g. PDU session establishment from the UE 100 to aSMF 160, via the AMF 155.

In an example, for any service request, the AMF 155 may respond with aservice accept message to synchronize PDU session status between the UE100 and network. The AMF 155 may respond with a service reject messageto the UE 100, if the service request may not be accepted by thenetwork. The service reject message may include an indication or causecode requesting the UE 100 to perform a registration update procedure.In an example, for service request due to user data, network may takefurther actions if user plane connection activation may not besuccessful. In an example FIG. 10 and FIG. 11, more than one UPF, e.g.,old UPF 110-2 and PDU session Anchor PSA UPF 110-3 may be involved.

In an example, the UE 100 may send to a (R)AN 105 an AN messagecomprising AN parameters, mobility management, MM NAS service request(e.g., list of PDU sessions to be activated, list of allowed PDUsessions, security parameters, PDU session status, and/or the like),and/or the like. In an example, the UE 100 may provide the list of PDUsessions to be activated when the UE 100 may re-activate the PDUsession(s). The list of allowed PDU sessions may be provided by the UE100 when the service request may be a response of a paging or a NASnotification, and may identify the PDU sessions that may be transferredor associated to the access on which the service request may be sent. Inan example, for the case of NG-RAN, the AN parameters may includeselected PLMN ID, and an establishment cause. The establishment causemay provide the reason for requesting the establishment of an RRCconnection. The UE 100 may send NAS service request message towards theAMF 155 encapsulated in an RRC message to the RAN 105.

In an example, if the service request may be triggered for user data,the UE 100 may identify, using the list of PDU sessions to be activated,the PDU session(s) for which the UP connections are to be activated inthe NAS service request message. If the service request may be triggeredfor signaling, the UE 100 may not identify any PDU session(s). If thisprocedure may be triggered for paging response, and/or the UE 100 mayhave at the same time user data to be transferred, the UE 100 mayidentify the PDU session(s) whose UP connections may be activated in MMNAS service request message, by the list of PDU sessions to beactivated.

In an example, if the service request over 3GPP access may be triggeredin response to a paging indicating non-3GPP access, the NAS servicerequest message may identify in the list of allowed PDU sessions thelist of PDU sessions associated with the non-3GPP access that may bere-activated over 3GPP. In an example, the PDU session status mayindicate the PDU sessions available in the UE 100. In an example, the UE100 may not trigger the service request procedure for a PDU sessioncorresponding to a LADN when the UE 100 may be outside the area ofavailability of the LADN. The UE 100 may not identify such PDUsession(s) in the list of PDU sessions to be activated, if the servicerequest may be triggered for other reasons.

In an example, the (R)AN 105 may send to AMF 155 an N2 Message (e.g., aservice request) comprising N2 parameters, MM NAS service request,and/or the like. The AMF 155 may reject the N2 message if it may not beable to handle the service request. In an example, if NG-RAN may beused, the N2 parameters may include the 5G-GUTI, selected PLMN ID,location information, RAT type, establishment cause, and/or the like. Inan example, the 5G-GUTI may be obtained in RRC procedure and the (R)AN105 may select the AMF 155 according to the 5G-GUTI. In an example, thelocation information and RAT type may relate to the cell in which the UE100 may be camping. In an example, based on the PDU session status, theAMF 155 may initiate PDU session release procedure in the network forthe PDU sessions whose PDU session ID(s) may be indicated by the UE 100as not available.

In an example, if the service request was not sent integrity protectedor integrity protection verification failed, the AMF 155 may initiate aNAS authentication/security procedure.

In an example, if the UE 100 triggers the service request to establish asignaling connection, upon successful establishment of the signalingconnection, the UE 100 and the network may exchange NAS signaling.

In an example the AMF 155 may send to the SMF 160 a PDU session updatecontext request (e.g., Nsmf_PDUSession_UpdateSMContext requestcomprising PDU session ID(s), Cause(s), UE 100 location information,access type, and/or the like).

In an example, the Nsmf_PDUSession_UpdateSMContext request may beinvoked by the AMF 155 if the UE 100 may identify PDU session(s) to beactivated in the NAS service request message. In an example, theNsmf_PDUSession_UpdateSMContext request may be triggered by the SMF 160wherein the PDU session(s) identified by the UE 100 may correlate toother PDU session ID(s) than the one triggering the procedure. In anexample, the Nsmf_PDUSession_UpdateSMContext request may be triggered bythe SMF 160 wherein the current UE 100 location may be outside the areaof validity for the N2 information provided by the SMF 160 during anetwork triggered service request procedure. The AMF 155 may not sendthe N2 information provided by the SMF 160 during the network triggeredservice request procedure.

In an example, the AMF 155 may determine the PDU session(s) to beactivated and may send an Nsmf_PDUSession_UpdateSMContext request to SMF160(s) associated with the PDU session(s) with cause set to indicateestablishment of user plane resources for the PDU session(s).

In an example, if the procedure may be triggered in response to pagingindicating non-3GPP access, and the list of allowed PDU sessionsprovided by the UE 100 may not include the PDU session for which the UE100 was paged, the AMF 155 may notify the SMF 160 that the user planefor the PDU session may not be re-activated. The service requestprocedure may succeed without re-activating the user plane of any PDUsessions, and the AMF 155 may notify the UE 100.

In an example, if the PDU session ID may correspond to a LADN and theSMF 160 may determine that the UE 100 may be outside the area ofavailability of the LADN based on the UE 100 location reporting from theAMF 155, the SMF 160 may decide to (based on local policies) keep thePDU session, may reject the activation of user plane connection for thePDU session and may inform the AMF 155. In an example, if the proceduremay be triggered by a network triggered service request, the SMF 160 maynotify the UPF 110 that originated the data notification to discarddownlink data for the PDU sessions and/or to not provide further datanotification messages. The SMF 160 may respond to the AMF 155 with anappropriate reject cause and the user plane activation of PDU sessionmay be stopped.

In an example, if the PDU session ID may correspond to a LADN and theSMF 160 may determine that the UE 100 may be outside the area ofavailability of the LADN based on the UE 100 location reporting from theAMF 155, the SMF 160 may decide to (based on local policies) release thePDU session. The SMF 160 may locally release the PDU session and mayinform the AMF 155 that the PDU session may be released. The SMF 160 mayrespond to the AMF 155 with an appropriate reject cause and the userplane Activation of PDU session may be stopped.

In an example, if the UP activation of the PDU session may be acceptedby the SMF 160, based on the location info received from the AMF 155,the SMF 160 may check the UPF 110 Selection 1025 Criteria (e.g., UPF's110 dynamic load, UPF's 110 relative static capacity among UPFssupporting the same DNN, UPF 110 location available at the SMF 160, UE100 location information, Capability of the UPF 110 and thefunctionality required for the particular UE 100 session. In an example,an appropriate UPF 110 may be selected by matching the functionality andfeatures required for a UE 100, DNN, PDU session type (i.e. IPv4, IPv6,ethernet type or unstructured type) and if applicable, the static IPaddress/prefix, SSC mode selected for the PDU session, UE 100subscription profile in UDM 140, DNAI as included in the PCC rules,local operator policies, S-NSSAI, access technology being used by the UE100, UPF 110 logical topology, and/or the like), and may determine toperform one or more of the following: continue using the current UPF(s);may select a new intermediate UPF 110 (or add/remove an intermediate UPF110), if the UE 100 has moved out of the service area of the UPF 110that was previously connecting to the (R)AN 105, while maintaining theUPF(s) acting as PDU session anchor; may trigger re-establishment of thePDU session to perform relocation/reallocation of the UPF 110 acting asPDU session anchor, e.g. the UE 100 has moved out of the service area ofthe anchor UPF 110 which is connecting to RAN 105.

In an example, the SMF 160 may send to the UPF 110 (e.g., newintermediate UPF 110) an N4 session establishment request. In anexample, if the SMF 160 may select a new UPF 110 to act as intermediateUPF 110-2 for the PDU session, or if the SMF 160 may select to insert anintermediate UPF 110 for a PDU session which may not have anintermediate UPF 110-2, an N4 session establishment request 100 messagemay be sent to the new UPF 110, providing packet detection, dataforwarding, enforcement and reporting rules to be installed on the newintermediate UPF. The PDU session anchor addressing information (on N9)for this PDU session may be provided to the intermediate UPF 110-2.

In an example, if a new UPF 110 is selected by the SMF 160 to replacethe old (intermediate) UPF 110-2, the SMF 160 may include a dataforwarding indication. The data forwarding indication may indicate tothe UPF 110 that a second tunnel endpoint may be reserved for bufferedDL data from the old I-UPF.

In an example, the new UPF 110 (intermediate) may send to SMF 160 an N4session establishment response message. In case the UPF 110 may allocateCN tunnel info, the UPF 110 may provide DL CN tunnel info for the UPF110 acting as PDU session anchor and UL CN tunnel info (e.g., CN N3tunnel info) to the SMF 160. If the data forwarding indication may bereceived, the new (intermediate) UPF 110 acting as N3 terminating pointmay send DL CN tunnel info for the old (intermediate) UPF 110-2 to theSMF 160. The SMF 160 may start a timer, to release the resource in theold intermediate UPF 110-2.

In an example, if the SMF 160 may select a new intermediate UPF 110 forthe PDU session or may remove the old I-UPF 110-2, the SMF 160 may sendN4 session modification request message to PDU session anchor, PSA UPF110-3, providing the data forwarding indication and DL tunnelinformation from new intermediate UPF 110.

In an example, if the new intermediate UPF 110 may be added for the PDUsession, the (PSA) UPF 110-3 may begin to send the DL data to the newI-UPF 110 as indicated in the DL tunnel information.

In an example, if the service request may be triggered by the network,and the SMF 160 may remove the old I-UPF 110-2 and may not replace theold I-UPF 110-2 with the new I-UPF 110, the SMF 160 may include the dataforwarding indication in the request. The data forwarding indication mayindicate to the (PSA) UPF 110-3 that a second tunnel endpoint may bereserved for buffered DL data from the old I-UPF 110-2. In this case,the PSA UPF 110-3 may begin to buffer the DL data it may receive at thesame time from the N6 interface.

In an example, the PSA UPF 110-3 (PSA) may send to the SMF 160 an N4session modification response. In an example, if the data forwardingindication may be received, the PSA UPF 110-3 may become as N3terminating point and may send CN DL tunnel info for the old(intermediate) UPF 110-2 to the SMF 160. The SMF 160 may start a timer,to release the resource in old intermediate UPF 110-2 if there is one.

In an example, the SMF 160 may send to the old UPF 110-2 an N4 sessionmodification request (e.g., may comprise new UPF 110 address, new UPF110 DL tunnel ID, and/or the like). In an example, if the servicerequest may be triggered by the network, and/or the SMF 160 may removethe old (intermediate) UPF 110-2, the SMF 160 may send the N4 sessionmodification request message to the old (intermediate) UPF 110-2, andmay provide the DL tunnel information for the buffered DL data. If theSMF 160 may allocate new I-UPF 110, the DL tunnel information is fromthe new (intermediate) UPF 110 may act as N3 terminating point. If theSMF 160 may not allocate a new I-UPF 110, the DL tunnel information maybe from the new UPF 110 (PSA) 110-3 acting as N3 terminating point. TheSMF 160 may start a timer to monitor the forwarding tunnel. In anexample, the old (intermediate) UPF 110-2 may send N4 sessionmodification response message to the SMF 160.

In an example, if the I-UPF 110-2 may be relocated and forwarding tunnelwas established to the new I-UPF 110, the old (intermediate) UPF 110-2may forward its buffered data to the new (intermediate) UPF 110 actingas N3 terminating point. In an example, if the old I-UPF 110-2 may beremoved and the new I-UPF 110 may not be assigned for the PDU sessionand forwarding tunnel may be established to the UPF 110 (PSA) 110-3, theold (intermediate) UPF 110-2 may forward its buffered data to the UPF110 (PSA) 110-3 acting as N3 terminating point.

In an example, the SMF 160 may send to the AMF 155 an N11 message e.g.,a Nsmf_PDUSession_UpdateSMContext response (comprising: N1 SM container(PDU session ID, PDU session re-establishment indication), N2 SMinformation (PDU session ID, QoS profile, CN N3 tunnel info, S-NSSAI),Cause), upon reception of the Nsmf_PDUSession_UpdateSMContext requestwith a cause including e.g., establishment of user plane resources. TheSMF 160 may determine whether UPF 110 reallocation may be performed,based on the UE 100 location information, UPF 110 service area andoperator policies. In an example, for a PDU session that the SMF 160 maydetermine to be served by the current UPF 110, e.g., PDU session anchoror intermediate UPF, the SMF 160 may generate N2 SM information and maysend an Nsmf_PDUSession_UpdateSMContext response to the AMF 155 toestablish the user plane(s). The N2 SM information may containinformation that the AMF 155 may provide to the RAN 105. In an example,for a PDU session that the SMF 160 may determine as requiring a UPF 110relocation for PDU session anchor UPF, the SMF 160 may reject theactivation of UP of the PDU session by sendingNsmf_PDUSession_UpdateSMContext response that may contain N1 SMcontainer to the UE 100 via the AMF 155. The N1 SM container may includethe corresponding PDU session ID and PDU session re-establishmentindication.

Upon reception of the Namf_EventExposure_Notify from the AMF 155 to theSMF 160, with an indication that the UE 100 is reachable, if the SMF 160may have pending DL data, the SMF 160 may invoke theNamf_Communication_N1N2MessageTransfer service operation to the AMF 155to establish the user plane(s) for the PDU sessions. In an example, theSMF 160 may resume sending DL data notifications to the AMF 155 in caseof DL data.

In an example, the SMF 160 may send a message to the AMF 155 to rejectthe activation of UP of the PDU session by including a cause in theNsmf_PDUSession_UpdateSMContext response if the PDU session maycorrespond to a LADN and the UE 100 may be outside the area ofavailability of the LADN, or if the AMF 155 may notify the SMF 160 thatthe UE 100 may be reachable for regulatory prioritized service, and thePDU session to be activated may not for a regulatory prioritizedservice; or if the SMF 160 may decide to perform PSA UPF 110-3relocation for the requested PDU session.

In an example, the AMF 155 may send to the (R)AN 105 an N2 requestmessage (e.g., N2 SM information received from SMF 160, securitycontext, AMF 155 signaling connection ID, handover restriction list, MMNAS service accept, list of recommended cells/TAs/NG-RAN nodeidentifiers). In an example, the RAN 105 may store the security context,AMF 155 signaling connection Id, QoS information for the QoS flows ofthe PDU sessions that may be activated and N3 tunnel IDs in the UE 100RAN 105 context. In an example, the MM NAS service accept may includePDU session status in the AMF 155. If the activation of UP of a PDUsession may be rejected by the SMF 160, the MM NAS service accept mayinclude the PDU session ID and the reason why the user plane resourcesmay not be activated (e.g. LADN not available). Local PDU sessionrelease during the session request procedure may be indicated to the UE100 via the session Status.

In an example, if there are multiple PDU sessions that may involvemultiple SMF 160 s, the AMF 155 may not wait for responses from SMF 160sbefore it may send N2 SM information to the UE 100. The AMF 155 may waitfor responses from the SMF 160 s before it may send MM NAS serviceaccept message to the UE 100.

In an example, the AMF 155 may include at least one N2 SM informationfrom the SMF 160 if the procedure may be triggered for PDU session userplane activation. AMF 155 may send additional N2 SM information from SMF160s in separate N2 message(s) (e.g. N2 tunnel setup request), if thereis any. Alternatively, if multiple SMF 160s may be involved, the AMF 155may send one N2 request message to (R)AN 105 after theNsmf_PDUSession_UpdateSMContext response service operations from theSMFs 160 associated with the UE 100 may be received. In such case, theN2 request message may include the N2 SM information received in one ormore of the Nsmf_PDUSession_UpdateSMContext response and PDU session IDto enable AMF 155 to associate responses to relevant SMF 160.

In an example, if the RAN 105 (e.g., NG RAN) node may provide the listof recommended cells/TAs/NG-RAN node identifiers during the AN releaseprocedure, the AMF 155 may include the information from the list in theN2 request. The RAN 105 may use this information to allocate the RAN 105notification area when the RAN 105 may decide to enable RRC inactivestate for the UE 100.

If the AMF 155 may receive an indication, from the SMF 160 during a PDUsession establishment procedure that the UE 100 may be using a PDUsession related to latency sensitive services, for any of the PDUsessions established for the UE 100 and the AMF 155 has received anindication from the UE 100 that may support the CM-CONNECTED with RRCinactive state, then the AMF 155 may include the UE's RRC inactiveassistance information. In an example, the AMF 155 based on networkconfiguration, may include the UE's RRC inactive assistance information.

In an example, the (R)AN 105 may send to the UE 100 a message to performRRC connection reconfiguration with the UE 100 depending on the QoSinformation for the QoS flows of the PDU sessions whose UP connectionsmay be activated and data radio bearers. In an example, the user planesecurity may be established.

In an example, if the N2 request may include a MM NAS service acceptmessage, the RAN 105 may forward the MM NAS service accept to the UE100. The UE 100 may locally delete context of PDU sessions that may notbe available in SGC.

In an example, if the N1 SM information may be transmitted to the UE 100and may indicate that some PDU session(s) may be re-established, the UE100 may initiate PDU session re-establishment for the PDU session(s)that may be re-established after the service request procedure may becomplete.

In an example, after the user plane radio resources may be setup, theuplink data from the UE 100 may be forwarded to the RAN 105. The RAN 105(e.g., NG-RAN) may send the uplink data to the UPF 110 address andtunnel ID provided.

In an example, the (R)AN 105 may send to the AMF 155 an N2 request Ack(e.g., N2 SM information (comprising: AN tunnel info, list of acceptedQoS flows for the PDU sessions whose UP connections are activated, listof rejected QoS flows for the PDU sessions whose UP connections areactivated)). In an example, the N2 request message may include N2 SMinformation(s), e.g. AN tunnel info. RAN 105 may respond N2 SMinformation with separate N2 message (e.g. N2 tunnel setup response). Inan example, if multiple N2 SM information are included in the N2 requestmessage, the N2 request Ack may include multiple N2 SM information andinformation to enable the AMF 155 to associate the responses to relevantSMF 160.

In an example, the AMF 155 may send to the SMF 160 aNsmf_PDUSession_UpdateSMContext request (N2 SM information (AN tunnelinfo), RAT type) per PDU session. If the AMF 155 may receive N2 SMinformation (one or multiple) from the RAN 105, then the AMF 155 mayforward the N2 SM information to the relevant SMF 160. If the UE 100time zone may change compared to the last reported UE 100 Time Zone thenthe AMF 155 may include the UE 100 time zone IE in theNsmf_PDUSession_UpdateSMContext request message.

In an example, if dynamic PCC is deployed, the SMF 160 may initiatenotification about new location information to the PCF 135 (ifsubscribed) by invoking an event exposure notification operation (e.g.,a Nsmf_EventExposure_Notify service operation). The PCF 135 may provideupdated policies by invoking a policy control update notificationmessage (e.g., a Npcf_SMPolicyControl_UpdateNotify operation).

In an example, if the SMF 160 may select a new UPF 110 to act asintermediate UPF 110 for the PDU session, the SMF 160 may initiates anN4 session modification procedure to the new I-UPF 110 and may provideAN tunnel info. The downlink data from the new I-UPF 110 may beforwarded to RAN 105 and UE 100. In an example, the UPF 110 may send tothe SMF 160, an N4 session modification response. In an example, the SMF160 may send to the AMF 155, an Nsmf_PDUSession_UpdateSMContextresponse.

In an example, if forwarding tunnel may be established to the new I-UPF110 and if the timer SMF 160 set for forwarding tunnel may be expired,the SMF 160 may sends N4 session modification request to new(intermediate) UPF 110 acting as N3 terminating point to release theforwarding tunnel. In an example, the new (intermediate) UPF 110 maysend to the SMF 160 an N4 session modification response. In an example,the SMF 160 may send to the PSA UPF 110-3 an N4 session modificationrequest, or N4 session release request. In an example, if the SMF 160may continue using the old UPF 110-2, the SMF 160 may send an N4 sessionmodification request, providing AN tunnel info. In an example, if theSMF 160 may select a new UPF 110 to act as intermediate UPF 110, and theold UPF 110-2 may not be PSA UPF 110-3, the SMF 160 may initiateresource release, after timer expires, by sending an N4 session releaserequest (release cause) to the old intermediate UPF 110-2.

In an example, the old intermediate UPF 110-2 may send to the SMF 160 anN4 session modification response or N4 session release response. The oldUPF 110-2 may acknowledge with the N4 session modification response orN4 session release response message to confirm the modification orrelease of resources. The AMF 155 may invoke theNamf_EventExposure_Notify service operation to notify the mobilityrelated events, after this procedure may complete, towards the NFs thatmay have subscribed for the events. In an example, the AMF 155 mayinvoke the Namf_EventExposure_Notify towards the SMF 160 if the SMF 160had subscribed for UE 100 moving into or out of area of interest and ifthe UE's current location may indicate that it may be moving into ormoving outside of the area of interest subscribed, or if the SMF 160 hadsubscribed for LADN DNN and if the UE 100 may be moving into or outsideof an area where the LADN is available, or if the UE 100 may be in MICOmode and the AMF 155 had notified an SMF 160 of the UE 100 beingunreachable and that SMF 160 may not send DL data notifications to theAMF 155, and the AMF 155 may informs the SMF 160 that the UE 100 isreachable, or if the SMF 160 had subscribed for UE 100 reachabilitystatus, then the AMF 155 may notify the UE 100 reachability.

An example PDU session establishment procedure depicted in FIG. 12 andFIG. 13. In an example embodiment, when the PDU session establishmentprocedure may be employed, the UE 100 may send to the AMF 155 a NASMessage (or a SM NAS message) comprising NSSAI, S-NSSAI (e.g., requestedS-NSSAI, allowed S-NSSAI, subscribed S-NSSAI, and/or the like), DNN, PDUsession ID, request type, old PDU session ID, N1 SM container (PDUsession establishment request), and/or the like. In an example, the UE100, in order to establish a new PDU session, may generate a new PDUsession ID. In an example, when emergency service may be required and anemergency PDU session may not already be established, the UE 100 mayinitiate the UE 100 requested PDU session establishment procedure with arequest type indicating emergency request. In an example, the UE 100 mayinitiate the UE 100 requested PDU session establishment procedure by thetransmission of the NAS message containing a PDU session establishmentrequest within the N1 SM container. The PDU session establishmentrequest may include a PDU type, SSC mode, protocol configurationoptions, and/or the like. In an example, the request type may indicateinitial request if the PDU session establishment is a request toestablish the new PDU session and may indicate existing PDU session ifthe request refers to an existing PDU session between 3GPP access andnon-3GPP access or to an existing PDN connection in EPC. In an example,the request type may indicate emergency request if the PDU sessionestablishment may be a request to establish a PDU session for emergencyservices. The request type may indicate existing emergency PDU sessionif the request refers to an existing PDU session for emergency servicesbetween 3GPP access and non-3GPP access. In an example, the NAS messagesent by the UE 100 may be encapsulated by the AN in a N2 message towardsthe AMF 155 that may include user location information and accesstechnology type information. In an example, the PDU sessionestablishment request message may contain SM PDU DN request containercontaining information for the PDU session authorization by the externalDN. In an example, if the procedure may be triggered for SSC mode 3operation, the UE 100 may include the old PDU session ID which mayindicate the PDU session ID of the on-going PDU session to be released,in the NAS message. The old PDU session ID may be an optional parameterwhich may be included in this case. In an example, the AMF 155 mayreceive from the AN the NAS message (e.g., NAS SM message) together withuser location information (e.g. cell ID in case of the RAN 105). In anexample, the UE 100 may not trigger a PDU session establishment for aPDU session corresponding to a LADN when the UE 100 is outside the areaof availability of the LADN.

In an example, the AMF 155 may determine that the NAS message or the SMNAS message may correspond to the request for the new PDU session basedon that request type indicates initial request and that the PDU sessionID may not be used for any existing PDU session(s) of the UE 100. If theNAS message does not contain an S-NSSAI, the AMF 155 may determine adefault S-NSSAI for the requested PDU session either according to the UE100 subscription, if it may contain only one default S-NSSAI, or basedon operator policy. In an example, the AMF 155 may perform SMF 160selection 1210 and select an SMF 160. If the request type may indicateinitial request or the request may be due to handover from EPS, the AMF155 may store an association of the S-NSSAI, the PDU session ID and aSMF 160 ID. In an example, if the request type is initial request and ifthe old PDU session ID indicating the existing PDU session may becontained in the message, the AMF 155 may select the SMF 160 and maystore an association of the new PDU session ID and the selected SMF 160ID.

In an example, the AMF 155 may send to the SMF 160, an N11 message,e.g., Nsmf_PDUSession_CreateSMContext request (comprising: SUPI or PEI,DNN, S-NSSAI, PDU session ID, AMF 155 ID, request type, N1 SM container(PDU session establishment request), user location information, accesstype, PEI, GPSI), or Nsmf_PDUSession_UpdateSMContext request (SUPI, DNN,S-NSSAI, PDU session ID, AMF 155 ID, request type, N1 SM container (PDUsession establishment request), user location information, access type,RAT type, PEI). In an example, if the AMF 155 may not have anassociation with the SMF 160 for the PDU session ID provided by the UE100 (e.g. when request type indicates initial request), the AMF 155 mayinvoke the Nsmf_PDUSession_CreateSMContext request, but if the AMF 155already has an association with an SMF 160 for the PDU session IDprovided by the UE 100 (e.g. when request type indicates existing PDUsession), the AMF 155 may invoke the Nsmf_PDUSession_UpdateSMContextrequest. In an example, the AMF 155 ID may be the UE's GUAMI whichuniquely identifies the AMF 155 serving the UE 100. The AMF 155 mayforward the PDU session ID together with the N1 SM container containingthe PDU session establishment request received from the UE 100. The AMF155 may provide the PEI instead of the SUPI when the UE 100 hasregistered for emergency services without providing the SUPI. In casethe UE 100 has registered for emergency services but has not beenauthenticated, the AMF 155 may indicate that the SUPI has not beenauthenticated.

In an example, if the request type may indicate neither emergencyrequest nor existing emergency PDU session and, if the SMF 160 has notyet registered and subscription data may not be available, the SMF 160may register with the UDM 140, and may retrieve subscription data 1225and subscribes to be notified when subscription data may be modified. Inan example, if the request type may indicate existing PDU session orexisting emergency PDU session, the SMF 160 may determine that therequest may be due to handover between 3GPP access and non-3GPP accessor due to handover from EPS. The SMF 160 may identify the existing PDUsession based on the PDU session ID. The SMF 160 may not create a new SMcontext but instead may update the existing SM context and may providethe representation of the updated SM context to the AMF 155 in theresponse. if the request type may be initial request and if the old PDUsession ID may be included in Nsmf_PDUSession_CreateSMContext request,the SMF 160 may identify the existing PDU session to be released basedon the old PDU session ID.

In an example, the SMF 160 may send to the AMF 155, the N11 messageresponse, e.g., either a PDU session create/update response,Nsmf_PDUSession_CreateSMContext response (cause, SM context ID or N1 SMcontainer (PDU session reject(cause))) or anNsmf_PDUSession_UpdateSMContext response.

In an example, if the SMF 160 may perform secondaryauthorization/authentication 1230 during the establishment of the PDUsession by a DN-AAA server, the SMF 160 may select a UPF 110 and maytrigger a PDU session establishment authentication/authorization.

In an example, if the request type may indicate initial request, the SMF160 may select an SSC mode for the PDU session. The SMF 160 may selectone or more UPFs as needed. In case of PDU type IPv4 or IPv6, the SMF160 may allocate an IP address/prefix for the PDU session. In case ofPDU type IPv6, the SMF 160 may allocate an interface identifier to theUE 100 for the UE 100 to build its link-local address. For UnstructuredPDU type the SMF 160 may allocate an IPv6 prefix for the PDU session andN6 point-to-point tunneling (based on UDP/IPv6).

In an example, if dynamic PCC is deployed, the may SMF 160 performs PCF135 selection 1235. If the request type indicates existing PDU sessionor existing emergency PDU session, the SMF 160 may use the PCF 135already selected for the PDU session. If dynamic PCC is not deployed,the SMF 160 may apply local policy.

In an example, the SMF 160 may perform a session management policyestablishment procedure to establish a PDU session with the PCF 135 andmay get the default PCC Rules for the PDU session. The GPSI may beincluded if available at the SMF 160. If the request type in 1215indicates existing PDU session, the SMF 160 may notify an eventpreviously subscribed by the PCF 135 by a session management policymodification procedure and the PCF 135 may update policy information inthe SMF 160. The PCF 135 may provide authorized session-AMBR and theauthorized 5QI and ARP to SMF 160. The PCF 135 may subscribe to the IPallocation/release event in the SMF 160 (and may subscribe otherevents).

In an example, the PCF 135, based on the emergency DNN, may set the ARPof the PCC rules to a value that may be reserved for emergency services.

In an example, if the request type in 1215 indicates initial request,the SMF 160 may select an SSC mode for the PDU session. The SMF 160 mayselect 1245 one or more UPFs as needed. In case of PDU type IPv4 orIPv6, the SMF 160 may allocate an IP address/prefix for the PDU session.In case of PDU type IPv6, the SMF 160 may allocate an interfaceidentifier to the UE 100 for the UE 100 to build its link-local address.For unstructured PDU type the SMF 160 may allocate an IPv6 prefix forthe PDU session and N6 point-to-point tunneling (e.g., based onUDP/IPv6). In an example, for Ethernet PDU type PDU session, neither aMAC nor an IP address may be allocated by the SMF 160 to the UE 100 forthis PDU session.

In an example, if the request type in 1215 is existing PDU session, theSMF 160 may maintain the same IP address/prefix that may be allocated tothe UE 100 in the source network.

In an example, if the request type in 1215 indicates existing PDUsession referring to an existing PDU session moved between 3GPP accessand non-3GPP access, the SMF 160 may maintain the SSC mode of the PDUsession, e.g., the current PDU session Anchor and IP address. In anexample, the SMF 160 may trigger e.g. new intermediate UPF 110 insertionor allocation of a new UPF 110. In an example, if the request typeindicates emergency request, the SMF 160 may select 1245 the UPF 110 andmay select SSC mode 1.

In an example, the SMF 160 may perform a session management policymodification 1250 procedure to report some event to the PCF 135 that haspreviously subscribed. If request type is initial request and dynamicPCC is deployed and PDU type is IPv4 or IPv6, the SMF 160 may notify thePCF 135 (that has previously subscribed) with the allocated UE 100 IPaddress/prefix.

In an example, the PCF 135 may provide updated policies to the SMF 160.The PCF 135 may provide authorized session-AMBR and the authorized 5QIand ARP to the SMF 160.

In an example, if request type indicates initial request, the SMF 160may initiate an N4 session establishment procedure with the selected UPF110. The SMF 160 may initiate an N4 session modification procedure withthe selected UPF 110. In an example, the SMF 160 may send an N4 sessionestablishment/modification request to the UPF 110 and may provide packetdetection, enforcement, reporting rules, and/or the like to be installedon the UPF 110 for this PDU session. If CN tunnel info is allocated bythe SMF 160, the CN tunnel info may be provided to the UPF 110. If theselective user plane deactivation is required for this PDU session, theSMF 160 may determine the Inactivity Timer and may provide it to the UPF110. In an example, the UPF 110 may acknowledges by sending an N4session establishment/modification response. If CN tunnel info isallocated by the UPF, the CN tunnel info may be provided to SMF 160. Inan example, if multiple UPFs are selected for the PDU session, the SMF160 may initiate N4 session establishment/modification procedure withone or more UPFs 110 of the PDU session.

In an example, the SMF 160 may send to the AMF 155 anNamf_Communication_N1N2MessageTransfer message (comprising PDU sessionID, access type, N2 SM information (PDU session ID, QFI(s), QoSprofile(s), CN tunnel info, S-NSSAI, session-AMBR, PDU session type,and/or the like), N1 SM container (PDU session establishment accept (QoSRule(s), selected SSC mode, S-NSSAI, allocated IPv4 address, interfaceidentifier, session-AMBR, selected PDU session type, and/or the like))).In case of multiple UPFs are used for the PDU session, the CN tunnelinfo may comprise tunnel information related with the UPF 110 thatterminates N3. In an example, the N2 SM information may carryinformation that the AMF 155 may forward to the (R)AN 105 (e.g., the CNtunnel info corresponding to the core network address of the N3 tunnelcorresponding to the PDU session, one or multiple QoS profiles and thecorresponding QFIs may be provided to the (R)AN 105, the PDU session IDmay be used by AN signaling with the UE 100 to indicate to the UE 100the association between AN resources and a PDU session for the UE100,and/or the like). In an example, a PDU session may be associated to anS-NSSAI and a DNN. In an example, the N1 SM container may contain thePDU session establishment accept that the AMF 155 may provide to the UE100. In an example, multiple QoS rules and QoS profiles may be includedin the PDU session establishment accept within the N1 SM and in the N2SM information. In an example, theNamf_Communication_N1N2MessageTransfer may further comprise the PDUsession ID and information allowing the AMF 155 to know which accesstowards the UE 100 to use.

In an example, the AMF 155 may send to the (R)AN105 an N2 PDU sessionrequest (comprising N2 SM information, NAS message (PDU session ID, N1SM container (PDU session establishment accept, and/or the like))). Inan example, the AMF 155 may send the NAS message that may comprise PDUsession ID and PDU session establishment accept targeted to the UE 100and the N2 SM information received from the SMF 160 within the N2 PDUsession request to the (R)AN 105.

In an example, the (R)AN 105 may issue AN specific signaling exchangewith the UE 100 that may be related with the information received fromSMF 160. In an example, in case of a 3GPP RAN 105, an RRC connectionreconfiguration procedure may take place with the UE 100 to establishthe necessary RAN 105 resources related to the QoS Rules for the PDUsession request. In an example, (R)AN 105 may allocate (R)AN 105 N3tunnel information for the PDU session. In case of dual connectivity,the master RAN 105 node may assign some (zero or more) QFIs to be setupto a master RAN 105 node and others to the secondary RAN 105 node. TheAN tunnel info may comprise a tunnel endpoint for one or more involvedRAN 105 nodes, and the QFIs assigned to one or more tunnel endpoints. AQFI may be assigned to either the master RAN 105 node or the secondaryRAN 105 node. In an example, (R)AN 105 may forward the NAS message (PDUsession ID, N1 SM container (PDU session establishment accept)) to theUE 100. The (R)AN 105 may provide the NAS message to the UE 100 if thenecessary RAN 105 resources are established and the allocation of (R)AN105 tunnel information are successful.

In an example, the N2 PDU session response may comprise a PDU sessionID, cause, N2 SM information (PDU session ID, AN tunnel info, list ofaccepted/rejected QFI(s)), and/or the like. In an example, the AN tunnelinfo may correspond to the access network address of the N3 tunnelcorresponding to the PDU session.

In an example, the AMF 155 may forward the N2 SM information receivedfrom (R)AN 105 to the SMF 160 via a Nsmf_PDUSession_UpdateSMContextrequest (comprising: N2 SM information, request type, and/or the like).In an example, if the list of rejected QFI(s) is included in N2 SMinformation, the SMF 160 may release the rejected QFI(s) associated QoSprofiles.

In an example, the SMF 160 may initiate an N4 session modificationprocedure with the UPF110. The SMF 160 may provide AN tunnel info to theUPF 110 as well as the corresponding forwarding rules. In an example,the UPF 110 may provide an N4 session modification response to the SMF160.

In an example, the SMF 160 may send to the AMF 155 anNsmf_PDUSession_UpdateSMContext response (Cause). In an example, the SMF160 may subscribe to the UE 100 mobility event notification from the AMF155 (e.g. location reporting, UE 100 moving into or out of area ofinterest), after this step by invoking Namf_EventExposure_Subscribeservice operation. For LADN, the SMF 160 may subscribe to the UE 100moving into or out of LADN service area event notification by providingthe LADN DNN as an indicator for the area of interest. The AMF 155 mayforward relevant events subscribed by the SMF 160.

In an example, the SMF 160 may send to the AMF 155, aNsmf_PDUSession_SMContextStatusNotify (release). In an example, ifduring the procedure, any time the PDU session establishment is notsuccessful, the SMF 160 may inform the AMF 155 by invokingNsmf_PDUSession_SMContextStatusNotify(release). The SMF 160 may releasesany N4 session(s) created, any PDU session address if allocated (e.g. IPaddress) and may release the association with the PCF 135.

In an example, in case of PDU type IPv6, the SMF 160 may generate anIPv6 Router Advertisement and may send it to the UE 100 via N4 and theUPF 110.

In an example, if the PDU session may not be established, the SMF 160may unsubscribe to the modifications of session management subscriptiondata for the corresponding (SUPI, DNN, S-NSSAI), usingNudm_SDM_Unsubscribe (SUPI, DNN, S-NSSAI), if the SMF 160 is no morehandling a PDU session of the UE 100 for this (DNN, S-NSSAI). In anexample, if the PDU session may not be established, the SMF 160 mayderegister for the given PDU session using Nudm_UECM_Deregistration(SUPI, DNN, PDU session ID).

The 5G system may support CIoT and/or MTC capabilities to supportfrequent small data transmission, infrequent small data transmission.The small data may comprise data payload in the range of e.g., 10, 20,100 bytes or e.g., 1, 10, 20, 100(s) of kilo bytes.

In an example, CIoT features may support infrequent small datatransmissions for at least low complexity, power constrained, low datarate CIoT UEs, and/or the like. In an example, the devices (e.g. utilitymeters, sensors, low power devices, and/or the like) may be mobilethroughout their lifetime.

The end-to-end communications between the CIoT/MTC application in the UEand the CIoT/MTC application in the external network, may utilizeservices provided by the 3GPP system (e.g., 5GS). In an example, acapability server (e.g., a service capability server, SCS, and/or thelike) may provide the end-to-end communications between the CIoT/MTCapplication in the UE and the CIoT/MTC application in the externalnetwork.

The CIoT/MTC application in the external network may be hosted by anapplication server (AS), an application function (AF) and/or the like.In an example, the AS and/or the AF may employ an SCS for additionalvalue added services. The 3GPP system may provide transport, subscribermanagement and other communication services including variousarchitectural enhancements, device triggering via control plane/userplane, data transmission via control plane/user plane, and/or the like.

In an example, device triggering may enable the capability server (e.g.,SCS) to send information to the UE via the 3GPP network to trigger theUE to perform application specific actions. In an example, theapplication specific actions may comprise initiating communication withthe SCS via the control plane, and/or user plane. Device triggering maybe required when an IP address for the UE is not available or reachableby the SCS/AS, or AF.

A device trigger message may comprise information that may enable thenetwork to route the message to the appropriate UE and the UE to routethe message to the appropriate application. In an example, a triggerpayload may comprise the information destined to the application, theinformation to route the information, and/or the like. In an example,the trigger payload, upon the reception by the UE may provideinformation to the application that may trigger application relatedactions. The application in the UE may perform indicated actions, suchas for example to initiate immediate or later communication to theSCS/AS and/or AF, based on the information contained in the triggerpayload.

In an example, device triggering may be subscription based. Thesubscription may provide the information whether a UE is allowed to betriggered by a specific SCS, SCS/AS, AF, and/or the like. In an example,when device triggers are delivered via MT-SMS the serving nodes (e.g.,AMF, SMF, UPF, and/or the like) may provide the service towards aspecific UE based on the UE's subscription for MT-SMS and othersubscription parameters affecting MT-SMS service provision.

In an example, device triggering recall/replace functionality may allowa SCS, SCS/AS, or AF to recall or replace submitted trigger message(s)which are not yet delivered to the UE.

In an example, the 5GS may support functions for high latencycommunication, HLC. HLC may be used to handle mobile terminated (MT)communication with UEs being unreachable while using power savingfunctions e.g. UE power saving mode or extended idle mode DRX dependingon operator configuration. High latency may be the initial response timebefore normal exchange of packets is established. The initial responsetime may be the time it takes before a UE has woken up from its powersaving state and responded to the initial downlink packet(s).

In an example, high latency communication may be handled by an extendedbuffering of downlink data in a UPF, NEF, SMF, AMF, and/or the like. Inan example, extended buffering may be controlled by the AMF, SMF, and/orthe like. The AMF and/or the SMF may ask the UPF to buffer downlink datauntil the UE is expected to wake up from its power saving state.

In an example, if control plane CIoT optimization is used, high latencycommunication may be handled by the buffering of downlink data in theUPF, AMF, SMF and/or the like.

In an example, high latency communication may be handled by notificationprocedures. The SCS/AS or AF may request notification when a UE wakes upfrom its power saving state and sends downlink data to the UE when theUE is reachable. In an example, the notification procedure may beavailable based on monitoring event for UE reachability, monitoringevent for availability after data notification (e.g., DDN) failure,and/or the like.

In an example, the SCS/AS or AF may request a one-time UE reachabilitynotification when it wants to send data to the UE. In an example, theSCS/AS or AF may request repeated availability after DDN failurenotifications where each notification is triggered by a DDN failure i.e.the SCS/AS may send a downlink packet which is discarded by a corenetwork node (e.g., UPF, SMF, AMF) and may trigger the AMF or SMF tosend an event notification to the SCS/AS next time the UE wakes up.

In an example, the length of the power saving intervals used by thenetwork may determine the maximum latency for a UE. An SCS/AS or AF,which has a specific requirement on the maximum latency for UEs itcommunicates with, may provide its maximum latency requirement to thenetwork.

In an example embodiment, a reachability procedure may be employed toreach a UE. Elements of the reachability procedure may be used byservices such as SMS over NAS, data transmission for UEs in power savingmode, and/or the like. The reachability procedure may be employed by UEsthat are in RRC-IDLE, RRC-INACTIVE or RRC-CONNECTED states.

In an example embodiment as depicted in example FIG. 14, a UEreachability notification procedure may be employed.

In an example, during a registration or subscription update procedure, aUDM may inform an AMF of the identities (e.g. FQDNs, NF ID, and/or thelike) of the network functions (NF) that are authorized to requestnotifications on the reachability of the UE via a registration serviceprocedure such as Nudm_UECM_Registration, Nudm_SubscriberData_Updateservice operation, and/or the like.

In an example, if a service-related entity requests the UDM to providean indication regarding UE reachability, the UDM may check that theservice-related entity is authorized to perform this request on thesubscriber associated to the UE. In an example, if the entity is notauthorized, the request may be rejected (e.g. if the requesting entityis recognized as being a valid entity, but not authorized for thatsubscriber) or silently discarded (e.g. if the requesting entity is notrecognized).

In an example, the UDM may store the identity of the service-relatedentity and may set the URRP-AMF parameter to indicate that such requestis received. If the value of URRP-AMF parameter has changed from “notset” to “set”, the UDM may initiate Namf_EventExposure_Subscribe_serviceoperation (URRP-AMF) towards the AMF. The UDM may indicate if directnotification to the NF may be used. In an example, the UDM may triggerUE reachability notification request procedure with two different AMFsfor the UE which may be connected to 5G core network over 3GPP accessand non-3GPP access simultaneously. In an example, the UDM may triggerUE reachability notification request procedure with a mobilitymanagement entity, MME.

In an example, the AMF may check that the requesting entity isauthorized to perform the request on the subscriber. In an example, ifthe entity is not authorized, the request may be rejected (e.g. if therequesting entity is recognized as being a valid entity, but notauthorized for the subscriber) or silently discarded (e.g. if therequesting entity is not recognized).

In an example, if the AMF has a MM Context for the user or the UE, theAMF may set URRP-AMF to indicate the need to report to the UDMinformation regarding changes in UE reachability, e.g. when the next NASactivity with that UE is detected.

In an example, if the UE state in the AMF is CM-CONNECTED state, the AMFmay initiate N2 notification procedure with reporting type set to singleRRC-Connected state notification.

In an example embodiment as depicted in example FIG. 15, a UE activitynotification procedure may be employed for reachability of a UE.

In an example, an AMF may receive an (N1) NAS signaling for a UE inCM-IDLE that may imply UE reachability, e.g. a registration request orservice request message from the UE. In an example, AMF may receive an(N2) UE Notification or an (N2) Path Switch Request from the RAN for aUE in CM-CONNECTED state.

In an example, if the AMF has a MM context for the UE and the URRP-AMFis set to report once that the UE is reachable, the AMF may initiate anotification e.g., an Namf_EventExposure_Notify service operation (e.g.,comprising SUPI, UE-Reachable, and/or the like) message to the UDM ordirectly to the NF (if previously indicated to the AMF). The AMF mayclear the corresponding URRP-AMF for the UE.

In an example, when the UDM receives the Namf_EventExposure_Notifyservice operation (SUPI, UE-Reachable) message or Nudm_UECM_Registrationservice for a UE that has URRP-AMF set, the UDM may trigger appropriatenotifications to the NFs (e.g. SMSF or SMS-GMSC, NEF, and/or the like)that have subscribed to the UDM for the reachability notification.

In an example embodiment, 5GS may support small data communication usingan application programming interface (API) corresponding to e.g., T8API, Nm API, and/or the like. The API may support packet transmissionusing IP-based, non-IP based, and/or the like protocols on thesouthbound interface. A messaging function entity (e.g., a network IoTmessaging function, NIMF) may be employed. The NIMF may be an extensionwith an additional role for the 5G network exposure function (NEF), orit may be a new network function dedicated for small data communicationfor IoT/CIoT. In an example, the NIMF may be a new standalone networkfunction entity.

The NIMF or NEF for small data communication may be located in theoperator domain.

In an example, the NIMF may support a northbound Nm interface. On thenorthbound interface, the Small data network function may support forexample the T8 non-IP data delivery NIDD Nm API, unstructured Nm API,and/or the like.

In an example, the NIMF may support a southbound N6m interface. Thesouthbound interface may enable small data communication with differenttypes of CIoT devices using different protocol stacks. In an example,the southbound interface has a PDU session layer which may support PDUSessions of different types e.g., IPv4, IPv6, Ethernet, unstructured,non-IP, and/or the like. In an example, on top of the PDU session layerhigher layer IoT protocols may be employed and supported towards the UE,e.g. Lightweight machine to machine, LWM2M, non-IP data deliveryreliable data service, NIDD RDS, and/or the like.

The NIMF or NEF may store and forward small data. The southboundprotocols may be terminated in the NIMF or NEF. The NIMF may map or actas proxies between the northbound and southbound protocols.

In an example, the NIMF may support lawful intercept LI (message based),charging (message based, i.e. number of CIoT messages), and/or the like.

In an example, if encryption protocols (e.g., datagram transport layersecurity (DTLS)) are employed as part of the southboundinterface/connection, the NIMF may offer LI of unencrypted data.

In an example, when a UE establishes a PDU Session, as part of theregistration procedure, or attach procedure, for which DNN configurationindicates small data communication to be used, then the SMF may initiatea connection towards the NEF or NIMF corresponding to the NEF ID or NIMFID for the DNN.

In an example as depicted in example FIG. 16, the UE may request theestablishment of a PDU Session wherein an N4 session establishment inthe UPF may be performed as part of the PDU session establishment.

In an example FIG. 16, the SMF and the UPF may handshake their supportfor small data communication in a PFCP association setup. The UE mayrequest the establishment of a PDU session. The SMF may determine basedon e.g. DNN or local DNN configuration, that the PDU session may be usedfor small data communication. The SMF may select a UPF for small datacommunication for the UE and based on UE subscription information. TheSMF may send PFCP session establishment request to the selected UPF. TheSMF may include a usage reporting rule to invoke message basedreporting.

The SMF may send a PFCP small data messaging request (F-SEID) message tothe UPF providing additional information for the small datacommunication. The information may comprise F-SEID (to identify therelated PDU session), IMSI, external identifier(s), MSISDN, UE IPaddress, PDU session type, PDU session ID, serving PLMN rate control,PCO parameters, serving PLMN ID, IMEISV, and/or the like.

The UPF-NEF may store the received information and may acknowledge tothe SMF that small data communication with NIDD API towards AF (i.e.SCS/AS) has been established.

UL and DL small data transmissions may take place using IP data orUnstructured (Non-IP) data depending on the PDU session type used by theUE. Higher layer protocols to employ may be decided by application layerinteractions between UE and NEF/NIMF or by DN configuration. Examples ofhigher layer protocols may comprise Lightweight M2M, CoAP, MQTT, DTLS,HTTP, HTTP/2, XMPP, AMQP, Reliable Data Service (RDS), LoRA, and/or thelike. In an example, PDU session deletion may be initiated and the PDUsession and the small data messaging context may be released in the UPF.

In an example FIG. 16, a connection may be established between the UPFand the NEF/NIMF for the PDU Session. The NEF/NIMF may store the IPaddress of the PDU Session, the IMSI and the External ID or MSISDN ofthe UE, the IP version to use (IPv6, IPv4 or Unstructured), and PCO. Inan example, for unstructured PDU session when point-to-point tunnelingbased on UDP/IP encapsulation is used, the UPF may store the forwardingIP address to the selected NIMF. For PDU sessions of type IP, theforwarding to the NIMF may be controlled by IP destination address usedat the higher layer protocol (e.g., LWM2M).

In an example, uplink and downlink data transmissions may take placeusing IP data or Unstructured (Non-IP) data depending on the PDU Sessiontype used by the UE.

In an example, when PDU Session release is initiated, the connectionbetween the UPF and the NIMF may be released. The NIMF may remove thestored IP address of the PDU session, and may mark the UE as inactive,and may close the connection for (small) data transmissions to/from theUE. The N4 Session may be released in the UPF.

In an example embodiment as depicted in example FIG. 17, the 5GS maysupport unstructured data transmission or non-IP data transmission(NIDD). The UE may support a NIDD client, for delivery of Unstructured(Non-IP) data. The SCS/AS or AF may send and receive messages to/from agiven UE identified by an External Identifier, MSISDN, and/or the like.The UE may have an Unstructured PDU session activated and the message onthe Nm or T8 API may be mapped to DL non-IP data PDU or from UL non-IPdata PDU delivered to/from the UE. In an example, for the direct modelcase, the DL and UL data PDUs may be transmitted directly between theUPF and the SCS/AS or AF.

In an example, an SCS/AS or AF may send a MT submit request with smalldata using T8 API, Nm API, and/or the like to a NEF or a NIMF.

The NIMF/NEF may determine the UE based on established connections andthe external identifier or MSISDN included in the MT submit request. TheNIMF may perform authorization and quota checks. If there is noestablished connection corresponding to the external identifier orMSISDN, the NIMF may send a MT submit response with appropriate errorcause value. In an example, if there is no established connectioncorresponding to the external identifier or MSISDN, the NIMF/NEF mayperform device triggering towards the UE to establish a connection.

The NIMF may sends a DL data PDU towards the UE using the IP addressassociated with the connection established by the UE. If the NIMFexpects no acknowledgement on the message with the DL data PDU, the NIMFmay sends a MT submit response to the SCS/AS informing that anunacknowledged transmission to the UE has been made.

In an example, the UE may send an UL data PDU to the NIMF. The NIMF maydetermine if the received UL data is an acknowledgement of the DL data.If the UL data PDU is an acknowledgement, the NIMF may send a MT SubmitResponse to the SCS/AS informing that an acknowledged transmission tothe UE has been made.

In an example embodiment, a reliable data service (RDS) may be used bythe UE and NEF for reliable (small) data delivery of unstructured PDU.The RDS may provide a mechanism for the NEF to determine if the data wassuccessfully delivered to the UE and for the UE to determine if the datawas successfully delivered to the NEF. In an example, when a requestedacknowledgement is not received, the reliable data service mayretransmit the packet. In an example, the RDS may employ NAS transportbetween the UE and the AMF for small data delivery. This may apply toboth 3GPP and non-3GPP accesses. In an example, the RDS may requiresupport for the AMF determining the NEF for a UE. In an example, the NEFmay support subscription checking and actual transmission of MO/MT smalldata delivery by the NEF to the AF/UE. In an example, the RDS maysupport MO/MT small data delivery for both roaming and non-roamingscenarios, unstructured PDU, and/or API exposure for reliable dataservice towards 3rd party application providers.

In an example, during a registration procedure, a UE may provide RDSsupported indication over NAS signaling indicating the UE's capabilityfor support of RDS. In an example, the RDS supported indication mayindicate whether the UE may support reliable small data delivery overNAS via 3GPP access or via both 3GPP and non-3GPP access. If the corenetwork supports RDS functionality, the AMF may include RDS supportedindication to the UE, and whether RDS delivery over NAS via 3GPP accessor via both the 3GPP and non-3GPP access is accepted by the network.

In an example, RDS packets may be transmitted over NAS without the needto establish data radio bearers, via NAS transport message, which cancarry RDS payload. PDU session establishment may not be needed. The UEand network may support RDS protocol. In an example, when the RDS isenabled, a protocol may be used between the end-points, e.g., betweenthe UE and the NEF. The protocol may employ an RDS header to identify ifthe packet requires no acknowledgement, requires an acknowledgement, oris an acknowledgment and to allow detection and elimination of duplicatePDUs at the receiving endpoint. In an example, port numbers in theheader may be used to identify the application on the originator and toidentify the application on the receiver.

An example FIG. 18 depicts data transmission over NAS (e.g., MM-NAS andSM-NAS).

An example FIG. 19 depicts a reliable data service via control plane toan SCS/AS via an NEF. The scenarios depicted in FIG. 19 employ datatransmission through AMF and through AMF and SMF.

An example FIG. 20 depicts data transmission via user plane from awireless device to a data network and to a SCS/AS or an AF. The datatransmission may employ an NEF network function with a data transmissionsupport functionality.

An example FIG. 21 depicts an example of a network function registrationwith an NRF and configuration with an OAM. The network function may be aUPF as depicted in FIG. 21. The network function may be an NEF, NIMF,and/or the like.

A communication system (e.g., 3G, 4G, LTE, 5G, and/or the like) maysupport (small) data transmission for cellular Internet of things (CIoT)applications. A wireless device may establish a session for transmissionof UL and/or DL data that may be via N6 interface to a DN or towards anAF, AS, SCS/AS via an NEF.

The communication system may support data transmission (e.g., for CIoT)and may require to release NAS connection and user plane resources assoon as possible to save UE power, network resources, and/or the like.Release of resources after data transmission may be required for supportof small data transmissions, single packet transmission (UL or DL), dualpacket transmission (UL with subsequent DL, or DL with subsequent UL),multiple packet transmission (one or a few UL and/or one or a few DL (inany combination or order), and/or the like. When a DL data transmissionor data packet transmission is initiated and/or controlled by thenetwork, the existing solutions do not provide an efficient and reliablemethod for release of resources upon completion of the data packettransmission and may cause inefficient use of network resources.

Example embodiments provide solution on how to provide releaseassistance indicator (RAI) indicating an end of packet transmission fora packet data unit (PDU) session of a wireless device for downlink data.

Example embodiments provide efficient and reliable method for release ofnetwork resources for data packet transmission that isinitiated/controlled by the network.

In an example embodiment, a wireless device (a UE) may request releaseof a connection (e.g., signaling/control plane connection, user planeconnection, non-access stratum NAS connection, RRC connection, and/orthe like). The UE may send a request that may comprise a releaseassistance indication/indicator, release assistance information, end oftransmission, and/or the like to the network (e.g., to a core networkelement AMF, SMF, and/or the like or to a base station, RAN, NG-RAN,and/or the like). In an example, the release assistance indicator may beprovided by a UE, or by the network e.g., a core network function, aSMF, NEF, AF, SCS/AS, and/or the like. In an example, the releaseassistance indicator/indication may be employed by the network to informthe network whether or not a downlink/uplink data transmission (e.g.acknowledgement or response) subsequent to the uplink/downlink datatransmission is expected. Example FIG. 30, FIG. 31, and FIG. 32 depictexamples of information element of a release assistanceindication/indicator. In an example, when the release assistanceindicator is provided by the UE, the UE may provide the releaseassistance indicator/indication for uplink data transmission in anon-access stratum (NAS) message e.g., NAS-MM, NAS-SM, and/or the like.The UE may send release assistance indication to the AMF inside a NASPDU.

In an example, when the AMF receives a release assistance indicator(e.g., from a network element, SMF, NEF, AF, AS, SCS/AS, and/or thelike) for downlink data transmission, the AMF may handle the releaseassistance indicator/indication. If the release assistance indicationindicates that no further uplink or downlink data transmissions areexpected and unless the AMF is aware of other pending MT traffic, theAMF may request NG-RAN to release the UE context. In an example, the AMFmay determine to request release of the UE context based on a status ofone or more existing PDU sessions associated with the UE. In an example,the release assistance indication provided by the network (e.g., fromAS, SCS/As, AF) may indicate that one or more uplink data transmissionsubsequent to a downlink data transmission is expected. In an example,the release assistance indication provided by the network (e.g., fromAS, SCS/As, AF) may indicate that no downlink transmission subsequent toan uplink/downlink data transmission is expected. In an example, therelease assistance indication may indicate that one or moredownlink/uplink data transmission subsequent to an uplink/downlink datatransmission is expected. The AMF may request the base station (e.g.,NG-RAN) to release the UE context once the packet is transmitted to theUE via a UPF and the base station or the AMF has forwarded the downlinkNAS transport message with container type “SM data transfer” to the UEunless the AMF is aware of other pending MT traffic.

In an example embodiment, the UE may send release assistanceindication/indicator (RAI) via access stratum AS. The RAI may indicatewhether further uplink/downlink transmissions or only a single downlinktransmission is expected. When NG-RAN receives the RAI from the UE inAS, the NG-RAN may maintain the UE's RRC connection in case RRCconnection establishment procedure was performed/executed, and mayinclude an N2 RAI indication (e.g., no further uplink/downlinktransmissions or only a single downlink transmission, and/or the like)in a UE message or an uplink NAS transport message. The AMF may evaluatethe N2 RAI. If the N2 RAI indicates no further uplink/downlinktransmissions and the AMF is not aware of any pending downlink DL datafor the UE (e.g. a pending SMS or pending DL data buffered e.g. inSMF/UPF as part of extended buffering), the AMF may send the N2 UEcontext release command to NG-RAN as per the AN release procedure.

In an example, if the N2 RAI indicates only a single downlinktransmission is expected, the AMF may send the N2 UE context releasecommand to NG-RAN as per the AN release procedure once the AMF hasforwarded the next downlink NAS transport message with container type“SM data transfer” to the UE and unless the AMF is aware of otherpending MT traffic.

The release assistance indication in AS may support UP-based datadelivery. In this case the RAN may send the N2 UE context releaserequest including the N2 RAI to the AMF. The AMF may send the N2 UEcontext release command to NG-RAN unless the AMF is aware of otherpending MT traffic. The RAN may release the UE once it has received theN2 UE context release command from the AMF and once an outstanding UPdownlink transmission has been received.

In an example, the AN release procedure may comprise sending by the AMFto a base station a context release command The AMF may send to a basestation (RAN, NG-RAN, and/or the like) an N2 UE context release command(e.g., with a cause). The cause may indicate a cause received from (R)ANor a cause due to an AMF internal event. When an NG-RAN is employed, theAMF may send the UE context release command message to the NG-RAN node.The UE context release command message may comprise the AMF UE NGAP IDIE and the RAN UE NGAP ID IE.

Upon reception of the UE context release command message, the NG-RANnode may release signaling and user data transport resources and replywith a UE context release complete message.

If the RAN paging priority IE is included in the UE context releasecommand message, the NG-RAN node may employ the paging priority IE todetermine a priority for paging the UE in RRC_INACTIVE state. In anexample, a user location information IE may be included in the UEcontext release complete message. If the information on recommendedcells and RAN nodes for paging IE is included in the UE context releasecomplete message, the AMF may store the information and may use it forsubsequent paging.

If the (R)AN connection (e.g. RRC connection or NWu connection) with theUE is not already released, the (R)AN may request the UE to release the(R)AN connection. Upon receiving (R)AN connection release confirmationfrom the UE, the (R)AN may delete the UE's context.

The (R)AN (e.g., 3GPP AN, non-3GPP AN, and/or the like) may confirm theN2 release by returning an N2 UE context release complete (e.g., list ofPDU session ID(s) with active N3 user plane, UE radio capability, and/orthe like) message to the AMF. The list of PDU session ID(s) may indicatethe PDU sessions served by (R)AN of the UE. The AMF may store the UERadio Capability information received from the NG-RAN node. The N2signaling connection between the AMF and the (R)AN for the UE may bereleased. The (R)AN may provide a list of recommended cells/trackingareas TAs/NG-RAN node identifiers for paging to the AMF. In an example,for one or more of the PDU sessions in the N2 UE context releasecomplete, the AMF may invoke a Nsmf_PDUSession_UpdateSMContext Request(e.g., comprising: PDU session ID, PDU session deactivation, cause,operation type, and/or the like). The operation type may be set to UPdeactivate to indicate deactivation of user plane resources for the PDUSession. In an example, the SMF may send to a UPF an N4 sessionmodification request (e.g., AN or N3 UPF Tunnel info to be removed,Buffering on/off). The SMF may initiate an N4 session modificationprocedure indicating the need to remove tunnel info of AN or UPFterminating N3. Buffering on/off may indicate whether the UPF may bufferincoming DL PDU or not.

In an example, the UPF may send to the SMF an N4 session modificationresponse acknowledging the SMF request. In an example, the SMF may sendto the AMF an Nsmf_PDUSession_UpdateSMContext Response. Upon completionof the procedure, the AMF may consider the N2 and N3 as released and mayenter/transition to CM-IDLE state.

In an example embodiment, one or more PDU sessions may be establishedfor a wireless device (UE) for transmission of data packets. The datapackets may be for cellular IoT, small data transmission, and/or thelike. The PDU session may be established for transmission of datapackets via control plane (as depicted in example FIG. 18 and FIG. 19)or via user plane (as depicted in example FIG.20). In an example, thedata packets may be non-IP data as depicted in example FIG. 17.

In an example, a UPF may receive data packets from a data network (DN)or from an application server (AS), an SCS/AS, an application function(AF), and/or the like. In an example, the UPF may receive the datapackets via a network exposure function (NEF). In an example, the NEF,the DN, AS, SCS/AS, or AF may send the data packets to an SMF.

In an example embodiment as depicted in FIG. 22 and FIG. 24, a sessionor a connection (e.g., a PDU session, non-IP data delivery connection,and/or the like) between a UE and a DN, AS, AF, SCS/AS, and/or the likemay be established/configured. Data transmission between the AF, AS,SCS/AS may be via an NEF.

In an example, the AF may send a fourth message to the NEF. In anexample, the fourth message may comprise a data packet (e.g., DL data).The fourth message may comprise an RAI (e.g., a release assistanceindication/indicator/information, end of data transmission indication,and/or the like). In an example, the data packet may comprise the DLdata. In an example, the data packet may comprise the RAI. The datapacket transmission may be a packet transmission. In an example, the RAImay indicate that the data packet may be the last data to transmit andone or more uplink data may be expected, or no UL data may be expected.In an example, the RAI may comprise the indication of last packettransmission. If one or more UL data transmission is expected aftertransmission of the data packet or DL data, the RAI may further comprisea parameter indicating that one or more UL data packets may betransmitted, a number/count of packets, a time value (10 seconds, 20seconds, and/or the like) indicating a time duration for which UL datamay be received, and/or the like. In an example, the parameter may beemployed to trigger a resource release e.g., when the expected number ofUL packets are received or the duration of the time value is elapsed.

In an example, the NEF may send a first message to the UPF. The firstmessage may comprise the RAI, the data packet, and/or the like. If thefirst message comprises the data packet or the DL data, the UPF maysend/forward the data packet or the DL data to a base station via an N3interface, N3 tunnel. In an example, the UPF may send/forward the datapacket to an intermediate UPF via N9 interface. The UPF may send thedata packet to the wireless device via the base station. The UPF maysend the data packet to the base station via one or more intermediateUPF(s). In an example, the UPF may receive the first message from theNEF comprising the RAI. The first message may indicate the end of packettransmission, the last packet transmission, and/or the like for a PDUsession of the wireless device (UE). The first message may comprise thedata packet, the RAI, an identifier of the wireless device, anidentifier of an application (application ID) and/or the like. In anexample, when a control plane data transmission is employed, the UPF maysend/forward the data packet to the SMF.

In an example, the UPF may receive and/or detect the RAI via a packetheader, an NIDD service message, and/or the like.

In an example, a proxy function, a CIoT support function, and/or thelike may be employed or co-located in the UPF. In an example, the proxyfunction in the UPF node (e.g., the PSA-UPF) may apply headercompression/decompression, ciphering/deciphering, integrity protection,and/or the like.

In an example, PDU session establishment may comprise selecting an NEFfor CIoT data transmission, non-IP data delivery NIDD, and/or the likevia the UPF and/or the UPF/proxy function. In an example, an interfacemay be employed for interaction between the UPF and the NEF (e.g., Nxinterface, N6m interface, and/or the like). In an example, when the PDUsession establishment is performed, based on a subscription data, a DNN,invoke NEF selection indicator, and/or the like, the SMF may select anNEF for NIDD based on a UE subscription profile. The SMF may configurethe NEF and UPF anchor (e.g. PDU session anchor, PSA, packet data unitsession anchor UPF and/or the like) for data transfer for a UE ID, a PDUsession ID, and/or the like. The SMF may update the AMF with anidentifier of the NEF (e.g., NEF ID) via the NsmfPDUSession_CreateSMContext response in order for the AMF to invokeNamf_EventExposure_Notify (User Identity) service once the UE becomesreachable or is about to become reachable.

In an example, the AF, SCS/AS may activate the NIDD service for thewireless device, UE, and may have data packet (e.g., downlink data,downlink non-IP data, and/or the like) to send to the UE. The AF, orSCS/AS may send the fourth message to the NEF. In an example, the fourthmessage may be an MT NIDD submit request message comprising an externalidentifier or GPSI, the data packet, non-IP data, reliable data serviceconfiguration, maximum latency, priority, PDU session establishmentoption, and/or the like) message to the NEF. When the AF may send thelast data packet to the UE, the fourth message or the MT NIDD submitrequest may comprise the release assistance indicator/indication, RAI.

In an example, the NEF may determine the PDU session context based onthe DNN associated with the NIDD configuration and the user identity. Ifan NEF PDU session context corresponding to the external identifier orGPSI included in the MT NIDD submit request is found, the NEF may checkswhether the AF or SCS/AS is authorized to send NIDD request, that theAF, or SCS/AS has not exceeded the quota of data submission to the PDUsession, and/or the like. In an example, the PDU session establishmentoption in the MT NIDD submit request message may be employed. Based onthe PDU session establishment option, if no NEF PDU session context isfound, the NEF, depending/based on the PDU session establishment option,may send a NIDD submit response (cause) with appropriate error causevalue. The NEF based on the PDU session establishment option may performa device triggering procedure towards the UE to establish a PDU session.

In an example, if an NEF PDU session context corresponding to theexternal identifier or GPSI included in the fourth message (e.g., the MTNIDD submit request message), the NEF may send the first message to theUPF and/or the proxy function. In an example, the first message may be aNIDD submit request message comprising a user identity, PDU session ID,NEF ID, the data packet, non-IP data, NEF wait time, maximumre-transmission time, and/or the like toward the UPF and/or the proxyfunction. In an example, if the fourth message comprises the RAI, thefirst message may comprise the RAI.

In an example, the RAI may be transmitted via a packet header or non-IPdata packets, IP packets, ethernet, unstructured, and/or the like. In anexample, packet header may be employed to transmit the RAI indication. Apacket may comprise a payload, a header comprising one or more fields,and/or the like. In an example, one or more fields of the packet headermay be employed to indicate RAI, or an end marker. In an example, a flag(one or more bits, a block, and/or the like) of the packet header may beemployed to indicate a release request. In an example, a payload of thepacket may be employed to transmit and detect the RAI. The packet headermay employ/comprise a type, length, value TLV guideline to assist withthe detection and/or the detection rules of the packet. In an example,one or more detection rules may be configured in the UPF to detect theRAI.

In an example, the UPF may detect the RAI or may determine that the datapacket is the last data packet transmission, or no further downlink oruplink transmission is expected, and may trigger a reporting to the SMF.In an example, when the RAI indicates that UL data may betransmitted/expected after the DL data, the UPF may trigger thereporting procedure based on the indication RAI e.g., detecting thetransmission of the UL data, and/or the like. The reporting proceduremay be an N4 reporting, PFCP reporting, and/or the like. The PFCPsession report procedure may be employed by a UP function (e.g., theUPF) to report information related to the PFCP session to the CPfunction (e.g., the SMF).

In an example, the UPF may send the RAI to the SMF via a session (e.g.,an N4 session. PFCP session, and/or the like) established/configuredbetween the UPF and the SMF for the PDU session of the wireless device.In an example, the UPF may send a second message to the SMF. The secondmessage may indicate a release request. The second message may comprisean identifier of a session between the SMF and the UPF (e.g., an N4session identifier, PFCP session identifier, and/or the like), therelease assistance indicator RAI, and/or the like.

In an example, the second message may be a session report procedure(e.g., N4 reporting, PFCP reporting, and/or the like). The UP functionmay initiate the PFCP session report procedure to report informationrelated to an PFCP session to the CP function. The UP function may sendthe PFCP session report request message, identifying the PFCP sessionfor which the report is sent and including the information to bereported. When the UP function receives a PFCP session report responsewith the cause success, the UP function may consider the information tobe successfully delivered to the CP function. When the CP functionreceives an PFCP session report request message, the CP function (e.g.,the SMF) may send the PFCP session report response message with arejection cause indicating that session context is not found if theF-SEID included in the PFCP session report request message is unknown.The CP function may process the information being reported asappropriate and send an PFCP session report response with the causeindicating success or return an appropriate error cause value.

In an example, when N4 session reporting is employed, the UPF may sendan N4 report message (e.g., comprising an N4 session ID, the RAI, listof [reporting trigger, measurement information], and/or the like) to theSMF. In an example, the reporting trigger parameter may comprise theRAI. The reporting trigger parameter may comprise a name of the eventwhich triggered the report and a measurement information parameter thatmay comprise information that the SMF requested to be informed about.The SMF may identify the N4 session context based on the received N4session ID and may apply the reported information for the correspondingPDU session. The SMF may respond with an N4 report ACK message.

In an example embodiment, when the SMF receives the RAI from the UPF,the SMF may determine that the PDU session may be deactivated/released.In an example, the SMF may send a session modification request messageto the UPF indicating release/deactivation of user plane resources, userplane tunnel, user plane tunnel information associated with the PDUsession of the wireless device. The session modification request messagemay comprise the identifier of the session between the SMF and the UPF(e.g., the N4 session ID, identifier of the PFCP session, and/or thelike). In an example, the session modification request message maycomprise an N4 session modification request message, a PFCP sessionmodification request, an Sx session modification request, and/or thelike.

In an example, the SMF may initiate an N4 session release procedure torelease an intermediate UPF of N3 terminating point. If there are one ormore intermediate UPFs, the SMF may initiate the N4 release procedurefor one or more UPFs (intermediate UPFs) to be released. The SMF mayinitiate an N4 session modification procedure to the UPF (i.e. N9terminating point or PDU session anchor) connecting to the released(intermediate) UPF.

In an example, if the intermediate UPF(s) of N3 terminating point isreleased, the SMF may initiate an N4 Session Modification proceduretowards the UPF (PDU Session Anchor or another intermediate UPF)connecting to the released UPF, indicating the need to remove AN tunnelinfo for N3 tunnel of the PDU session of the wireless device. In anexample, the UPF connecting to the released UPF may buffer the DLpackets for the PDU session. In an example, N4 session modificationprocedure may be performed toward the UPF of N3 terminating point.

In an example, if the UPF of N3 terminating point is not released, theSMF may initiates an N4 session modification procedure indicating theneed to remove AN tunnel info for N3 tunnel of the PDU session. When thePDU session corresponds to a LADN, the SMF may notify the UPF to discarddownlink data for the PDU sessions and/or to not provide further datanotification messages.

In an example, the SMF may invoke anNamf_Communication_N1N2MessageTransfer service operation (comprising PDUsession ID, N2 SM information (N2 resource release request (PDU SessionID))) to release the NG-RAN resources associated with the PDU Session.

The AMF may send an N2 PDU session resource release command including N2SM information (N2 resource release request (PDU session ID)) receivedfrom the SMF via N2 to the NG-RAN.

The NG-RAN may issue NG-RAN signaling exchange (e.g. RRC connectionreconfiguration, and/or the like) with the UE to release the NG-RANresources related to the PDU session of the wireless device receivedfrom the AMF.

The NG-RAN may acknowledge the N2 PDU session resource release commandto the AMF including N2 SM resource release ack (user locationinformation).

The AMF may invoke an Nsmf_PDUSession_UpdateSMContext service operationto acknowledge the Namf_Communication_N1N2MessageTransfer serviceoperation.

In an example, when the SMF invokes theNamf_Communication_N1N2MessageTransfer service operation to release theNG-RAN resources associated with the PDU session, the AN releaseprocedure may be performed. The AN release procedure may comprisesending by the AMF to a base station (RAN, NG-RAN, and/or the like) acontext release command. The AMF may send to a base station (RAN,NG-RAN, and/or the like) an N2 UE context release command (e.g., with acause). The cause may indicate a cause received from (R)AN or a causedue to an AMF internal event. When an NG-RAN is employed, the AMF maysend the UE context release command message to the NG-RAN node. The UEcontext release command message may comprise the AMF UE NGAP ID IE andthe RAN UE NGAP ID IE.

Upon reception of the UE context release command message, the NG-RANnode may release signaling and user data transport resources and replywith the UE context release complete message.

If the RAN paging priority IE is included in the UE context releasecommand message, the NG-RAN node may employ the paging priority IE todetermine a priority for paging the UE in RRC_INACTIVE state. In anexample, a user location information IE may be included in the UEcontext release complete message. If the information on recommendedcells and RAN nodes for paging IE is included in the UE context releasecomplete message, the AMF may store the information and may use it forsubsequent paging.

If the (R)AN connection (e.g. RRC connection or NWu connection) with theUE is not already released, the (R)AN may request the UE to release the(R)AN connection. Upon receiving (R)AN connection release confirmationfrom the UE, the (R)AN may delete the UE's context.

The (R)AN may confirm the N2 release by returning an N2 UE contextrelease complete (e.g., list of PDU session ID(s) with active N3 userplane, UE radio capability, and/or the like) message to the AMF. Thelist of PDU session ID(s) may indicate the PDU sessions served by (R)ANof the UE. The AMF may store the UE Radio Capability informationreceived from the NG-RAN node. The N2 signaling connection between theAMF and the (R)AN for the UE may be released. The (R)AN may provide alist of recommended cells/tracking areas TAs/NG-RAN node identifiers forpaging to the AMF. In an example, for one or more of the PDU sessions inthe N2 UE context release complete, the AMF may invoke aNsmf_PDUSession_UpdateSMContext request (e.g., comprising: PDU sessionID, PDU session deactivation, cause, operation type, and/or the like).The operation type may be set to UP deactivate to indicate deactivationof user plane resources for the PDU Session. In an example, the SMF maysend to a UPF an N4 session modification request (e.g., AN or N3 UPFTunnel info to be removed, Buffering on/off). The SMF may initiate an N4session modification procedure indicating the need to remove tunnel infoof AN or UPF terminating N3. Buffering on/off may indicate whether theUPF may buffer incoming DL PDU or not.

In an example, the UPF may send to the SMF an N4 session modificationresponse acknowledging the SMF request. In an example, the SMF may sendto the AMF an Nsmf_PDUSession_UpdateSMContext Response. Upon completionof the procedure, the AMF may consider the N2 and N3 as released and mayenter/transition to CM-IDLE state.

In an example embodiment, a UPF may receive a first message from an NEF.The first message may indicate an end of packet transmission for a PDUsession of a wireless device. The first message may comprise an RAI, anidentifier of the wireless device, a data packet, and/or the like. TheUPF may send/forward the data packet to a base station via an N3 tunnelor to an intermediate UPF via an N9 interface. The UPF may release userplane tunnel, N3 tunnel information, and/or the like associated with thePDU session of the wireless device in response to receiving the firstmessage (e.g., comprising the RAI, the data packet, and/or the like)from the NEF. The UPF may send a second message or a release indicationmessage (e.g., comprising an identifier of a session between the SMF andthe UPF, the RAI, and/or the like) via an interface between the UPF andthe SMF e.g., N4 interface. The second message or the release indicationmessage may comprise an N4 reporting procedure. The SMF may send anacknowledgment to the UPF indicating the receipt or acknowledgment ofthe release indication message. The SMF may send/invoke to the AMF andin response to receiving the release indication message, anNamf_Communication_N1N2MessageTransfer service operation (comprising PDUsession ID, N2 SM information (N2 resource release request (PDU SessionID))) to release the NG-RAN resources associated with the PDU Session.

In an example embodiment as depicted in FIG. 25, the AF, SCS/AS may sendthe fourth message to the NEF. The fourth message may comprise the RAI.The NEF may send a first message to the SMF. The first message maycomprise the RAI. In an example, the first message may comprise anidentifier of the wireless device (e.g., UE ID, an address of UE, SUPI,GPSI, and/or the like), an identifier of the PDU session (e.g., PDUsession ID), and/or the like. In an example, when the fourth messagecomprises the data packet, or DL data, the NEF may send the data packetto the UPF. The UPF may send/forward the data packet, or the DL data tothe wireless device via the base station (e.g., via N3 interface, N3tunnel) or via an intermediate UPF (e.g., via N9 interface).

In an example embodiment, when the SMF receives the RAI from the NEF(e.g., via the first message), the SMF may determine that the PDUsession may be deactivated/released. In an example, the SMF may send asession modification request message to the UPF indicatingrelease/deactivation of user plane resources, user plane tunnelinformation associated with the PDU session of the wireless device. Thesession modification request message may comprise the identifier of thesession between the SMF and the UPF (e.g., the N4 session ID, identifierof the PFCP session, and/or the like).

In an example, the SMF may initiate the N4 session release procedure torelease an intermediate UPF of N3 terminating point. If there are one ormore intermediate UPFs, the SMF may initiate the N4 release procedurefor one or more UPFs (intermediate UPFs) to be released. The SMF mayinitiate an N4 session modification procedure to the UPF (i.e. N9terminating point or PDU session anchor) connecting to the released(intermediate) UPF.

In an example, if the intermediate UPF(s) of N3 terminating point isreleased, the SMF may initiate the N4 session modification proceduretowards the UPF (PDU session anchor or one or more intermediate UPF(s))connecting to the released UPF, indicating the need to remove AN tunnelinfo for N3 tunnel of the PDU session of the wireless device. In anexample, the UPF connecting to the released UPF may buffer the DLpackets for the PDU session. In an example, N4 session modificationprocedure may be performed toward the UPF of N3 terminating point.

In an example, if the UPF of N3 terminating point is not released, theSMF may initiates an N4 session modification procedure indicating theneed to remove AN tunnel info for N3 tunnel of the PDU session. When thePDU session corresponds to a LADN, the SMF may notify the UPF to discarddownlink data for the PDU sessions and/or to not provide further datanotification messages.

In an example, the SMF may send a third message to the AMF. The thirdmessage may comprise the RAI, the identifier of the PDU session (e.g.,PDU session ID), and/or the like. The third message may be via aninterface between the SMF and the AMF (e.g., N11 interface). In anexample, the third message may employ anNamf_Communication_N1N2MessageTransfer service operation. In an example,the SMF may invoke the Namf_Communication_N1N2MessageTransfer serviceoperation (comprising PDU session ID, N2 SM information (N2 resourcerelease request (PDU Session ID))) to release the NG-RAN resourcesassociated with the PDU Session.

The AMF may send an N2 PDU session resource release command including N2SM information (N2 resource release request (PDU session ID)) receivedfrom the SMF via N2 to the NG-RAN.

The NG-RAN may issue NG-RAN signaling exchange (e.g. RRC connectionreconfiguration, and/or the like) with the UE to release the NG-RANresources related to the PDU session of the wireless device receivedfrom the AMF.

The NG-RAN may acknowledge the N2 PDU session resource release commandto the AMF including N2 SM resource release ack (user locationinformation).

The AMF may invoke an Nsmf_PDUSession_UpdateSMContext service operationto acknowledge the Namf_Communication_N1N2MessageTransfer serviceoperation.

In an example, when the SMF invokes theNamf_Communication_N1N2MessageTransfer service operation to release theNG-RAN resources associated with the PDU Session, the AN releaseprocedure may be performed.

In an example embodiment as depicted in FIG. 28, one or more PDU sessionmay be established for a wireless device or associated to the wirelessdevice. In an example, the wireless device may have one or more PDUsession(s) associated with one or more AF(s), AS(s), SCS/AS(s), and/orthe like. When one or more AF(s) indicate an end of packet transmissionto request release of one or more PDU session(s) or release of UEconnections (e.g., transmit the RAI), one or more AF(s) may have one ormore PDU session(s) that may be active. In an example, the SMF uponreceiving the one or more RAI(s) for the one or more PDU session(s) ofthe wireless device, may determine if the wireless device has one ormore PDU sessions that are active and may not send an indication to theAMF to release the UE context or NAS connection of the UE. In anexample, the SMF may determine that the one ore RAI(s) or the RAI thatis received from the UPF or the NEF is the last RAI and UE signaling,control plane and user plane resources may be released. In an example,the SMF may determine to release the resources based a status of pendingdata transmission, determining that no UL or DL data transmission isexpected, and/or the like.

In an example embodiment, in response to receiving the one or moreRAI(s) or the RAI from the UPF or from the NEF, the SMF may send the RAIor the one or more RAI(s) to the AMF. In an example, the AMF maydetermine to release the UE NAS connection, release UE context, and/orthe like. In an example, the determining by the AMF may be based on theUE context information (e.g., one or more PDU sessions may be active),(status of) pending data transmission, and/or the like.

In an example as depicted in FIG. 28, the AMF may receive one or moreRAI(s) from one or more SMF(s). The one or more SMF(s) may receive oneor more RAI(s) from one or more UPF(s) or one or more NEF(s). The one ormore SMF(s) may send the RAI or the one or more RAI(s) to the AMF. In anexample, the AMF may determine to release the UE NAS connection, releaseUE context, and/or the like. In an example, the determining by the AMFmay be based on the UE context information (e.g., one or more PDUsessions may be active), (status of) pending data transmission (e.g.,pending mobile terminating MT or DL data, UL transmission expected inresponse to a DL data transmission, DL transmission expected in responseto an UL data transmission, and/or the like), and/or the like.

In an example embodiment, the UPF may receive from an NEF, a firstmessage. The first message may comprise a release assistance indicator(RAI). In an example, the first message may comprise a data packet. Ifthe first message comprises the data packet, the UPF may send the datapacket to the wireless device via a base station. The UPF may send thedata packet to the wireless device via an intermediate UPF and a basestation.

In an example, in response to receiving the RAI, the UPF may releaseuser plane resources, user plane tunnel, N3 tunnel information, and/orthe like.

The UPF may send the RAI to a SMF via a second message. The secondmessage may indicate a request to release the UE context, release the N4session (context). The second message may comprise the N4 reportingprocedure. The second message may comprise the RAI, an identifier of asession between the SMF and the UPF (e.g., the N4 session, N4 sessionID), and/or the like.

The SMF in response to receiving the second message may invoketheNamf_Communication_N1N2MessageTransfer service operation (comprisingPDU session ID, N2 SM information (N2 resource release request (PDUSession ID))) to release the NG-RAN resources associated with the PDUSession.

In an example embodiment as depicted in FIG. 27 and FIG. 29, small datafast path (SDFP) transmission may be employed for transmission of datapackets, DL data and/or UL data. The SDFP may be realized by providingrelevant UPF or PDU session related information to the UE from thenetwork. In an example, the UE may provide the information (e.g., theUPF or PDU session relevant information) to a RAN. The UPF or PDUsession relevant information may enable the RAN to determine/derive apath over N3 to the UPF. At UL data arrival the UE may send apacket/data packet comprising the data, the UPF or PDU session relevantinformation, and/or the like to the RAN. The RAN may forward/send thedata packet to the UPF via the N3 interface. In an example, the UPF orPDU session relevant information may be provided to the UE as part of asession management (SM) procedure or UE registration procedures. The SMFmay enable one (or more) of the QoS flows for SDFP. The AMF maydetermine/derive SDFP security information and may provide theinformation to the SMF. The SMF may retain/store the SDFP securityinformation for the PDU session, and may enable indicated QoS flows andmay acknowledge to the AMF that they have been SDFP enabled. In anexample, header compression may be supported in the UE and the UPF.

In an example, RAN may store/retain a list of UPFs that support SDFP,with an index and an IP address for one or more UPF(s) in the list. Thelist of UPFs supporting SDFP may be preconfigured in the RAN and one ormore RAN node(s) in the same UPF service area may have the sameinformation. In an example, when a PDU session is created for SDFP, oractivated by SMF, RAN may receive from the AMF/SMF a UPF tunnelinformation and a SDFP indication. Based on the IP address in the UPFtunnel information and the RAN list of UPFs with SDFP support, RAN maydetermine the UPF index. RAN may send the UPF index and the UPF N3 ULTEID to the UE.

In an example, when an UL data transmission is required, the UE may sendUL data packets by employing SDFP.

The UE may establish an RRC connection for SDFP transfer. The UE mayprovide parameters for selection of UPF for the PDU session for the UEto the RAN e.g., the UPF index and the UPF UL TEID. In an example, theparameters may be transmitted as part of UL data PDU.

In an example, the AMF may trigger paging towards RAN (e.g. due to N1 CPsignaling) during an ongoing SDFP transfer initiated by UL data, RAN mayset up N2 UE association using the 5G S-TMSI received from the UE andmay provide the AMF with NGAP RAN UE ID. The AMF may reply with NGAP AMFUE ID.

The UE may encrypt, and integrity protect a data packet or an UL dataPDU and may send it to the RAN.

The RAN may send/forward the UL data PDU on the N3 tunnel to a selectedUPF. RAN may select the UPF and the N3 tunnel based on the SDFPinformation provided by the UE (i.e. UPF index and the UPF UL TEID) andthe RAN preconfigured list of UPFs supporting SDFP. The RAN may providethe UPF with RAN N3 DL Tunnel Info for the SDFP session.

The UPF may check integrity protection and decrypt the UL data PDU. Ifpassed the check, the UPF send/forward the UL data on the N6/N9interface to a DN or to the NEF towards an AF, AS, SCS/AS, and/or thelike. The UPF may enable (subsequent) DL data transmissions to the RANnode when it receives the UP data PDU from N6/N9 interface or the DN,AF, SCS/AS, and/or the like. In an example, a DL data packet may arriveon N6/N9, e.g. an acknowledgement.

The UPF may encrypt and integrity protect the DL data PDU and maysend/forward it to the RAN node. The RAN node may forward the DL dataPDU to the UE.

In an example, based on a UP activity timeout timer in RAN and UPF theSDFP information context in RAN may be released and DL data transmissionin the UPF may be disabled by setting the SDFP in a non-active state. Inan example, the RAN node may release the RRC connection.

In an example embodiment, when the UPF receives a first messagecomprising a data packet and the RAI, release assistanceindication/indicator, release assistance information, and/or the like,the UPF may disable DL data transmission in the UPF. The UPF mayset/transition the state of SDFP to a non-active state. In an example,the UPF may send the data packet with the RAI to the UE via the RANnode. In response to receiving the RAI by the UE, the UE may send theRAI to the AMF and the AMF may initiate a release of NAS signalingand/or the RRC connection. In an example, the AMF may indicate to theRAN node to release the SDFP information context in the RAN node. In anexample, the UPF may send the data packet with the RAI to the RAN nodeand in response to receiving the RAI, the RAN node may detect the RAIindication and may release the SDFP information context in the RAN node.

In an example, SDFP may be initiated by DL data transmission. In anexample, the DL data may be received by the UPF from a DN via N6interface, or from the NEF. In an example, the DL data received by theUPF (e.g., from N6 or NEF) may be for a PDU session that is SDFPenabled. In an example the SDFP may require activation when the RAN N3DL TEID is unknown or expired.

In an example, the PDU Session may be in CM_IDLE. The UPF may send adata notification (e.g., downlink data notification) to the SMF. The SMFmay notifies the AMF via N11 interface and may employ anNamf_MT_EnableUEReachability service that may comprise a fast Pathindicator for DL SDFP transfer. The AMF may send a paging message to theRAN with a fast path FP indicator. The RAN may page the UE with the FPindicator included.

The UE may respond to the paging with an RRC establishment including aNAS service request. The fast path indicator in the received paging maytrigger the UE to include the UPF index and UPF UL TEID and a PDUsession ID. As part of the RRC establishment, the RAN and the UE mayestablish a data radio bearer (DRB) with default parameters for SDFPtransmissions.

In an example, RAN may determine/detect/understand based on the includedUPF index and UPF UL TEID that a SDFP may be established. The RAN nodemay allocate a RAN N3 TEID, and may map it to the DRB and may establisha N3 tunnel based on the SDFP information provided by the UE (e.g., UPFindex and the UPF UL TEID) and the RAN preconfigured list of UPFssupporting SDFP. The RAN node may send an initial UE message (e.g., NAS:service request, RAN N3 TEID, PDU session ID, and/or the like) to AMF.

The AMF may receive NAS service request as a response to the pagingrequest. AMF send a Nsmf_PDUSession_UpdateSMContext request message withthe NAS service request, RAN N3 TEID, PDU session ID included to the SMFwhich may handles the PDU session.

The SMF may determine/detect/understand based on the included RAN N3TEID that the PDU session may be moved/transitioned to active SDFPstate. The SMF may sends an N4 session modification request (comprisingRAN N3 TEID, PDU Session, Fast Path indicator, and/or the like) to theUPF. The UPF may store the RAN N3 TEID for the PDU session and mayopen/activate the PDU session for SDFP transmissions. The UPF mayacknowledge to the SMF by sending a N4 session modification responsemessage. The SMF may keep the UE in CM-IDLE and/or may keep a record ofthe SDFP transmission, e.g. in charging information, statistics, and/orthe like. The SMF may acknowledge to the AMF by sending aNsmf_PDUSession_UpdateSMContext response to the AMF. The UPF maysend/forward any buffered DL data to the RAN. The RAN node maysend/forward DL data to the UE.

In an example, when the UP activity timeout timer expires in UPF andRAN, the RAN may release the RRC connection, and the UPF may disable theSDFP and transition to non-active state.

In an example, based on a UP activity timeout timer in RAN and UPF theSDFP information context in RAN may be released and DL data transmissionin the UPF may be disabled by setting the SDFP in a non-active state. Inan example, the RAN node may release the RRC connection.

In an example embodiment, when the UPF receives a first messagecomprising a data packet and the RAI, release assistanceindication/indicator, release assistance information, and/or the like,the UPF may disable DL data transmission in the UPF. The UPF mayset/transition the state of SDFP to a non-active state. In an example,the UPF may send the data packet with the RAI to the UE via the RANnode. In response to receiving the RAI by the UE, the UE may send theRAI to the AMF via a NAS message and the AMF may initiate the release ofNAS signaling and/or the RRC connection. In an example, the AMF mayindicate to the RAN node to release the SDFP information context in theRAN node. In an example, the UPF may send the data packet with the RAIto the RAN node and in response to receiving the RAI, the RAN node maysend the data packet and the RAI to the UE. The RAN node may detect theRAI indication and may release the SDFP information context in the RANnode. The RAN node based on the RAI may send a release request messageto the AMF via N2 and the AMF may release the UE context and mayinitiate the release of NAS connection, RRC connection, and/or the like.

In an example embodiment, a user plane function (UPF) may receive from anetwork exposure function (NEF), a first message. The first message maycomprise a release assistance indicator indicating end of packettransmission for a packet data unit session of a wireless device. TheUPF may send to a session management function (SMF), a second messageindicating a release request. The second message may comprise anidentifier of a session between the SMF and the UPF, the releaseassistance indicator, and/or the like. The UPF may receive from the SMF,a session modification request message indicating release of user planetunnel and/or tunnel information. The session modification requestmessage may comprise the identifier of the session between the SMF andthe UPF. In an example, the UPF may release based on the sessionmodification request message, the user plane tunnel of the packet dataunit session of the wireless device.

In an example, the SMF may send to an access and mobility managementfunction (AMF), a third message. The third message may comprise therelease assistance indicator, an identifier of the packet data unitsession, and/or the like.

In an example, the AMF may determine to release a non-access stratumconnection of the wireless device. In an example, the AMF may determineto release the non-access stratum connection of the wireless devicebased on pending data packets for at least one packet data unit sessionof the wireless device. In an example, the release request may indicatedeactivation of the packet data unit session of the wireless device. Inan example, the identifier of the session may comprise an N4 sessionidentifier of an N4 session.

In an example, the NEF may receive from an application function, afourth message comprising the release assistance indicator. The fourthmessage may comprise a data packet, and/or the like. The fourth messagemay comprise an identifier of the wireless device, and/or the like.

In an example, the first message may comprise a data packet, and/or thelike. The UPF may determine, based on the indication, that the datapacket may be a last data packet for the packet data unit session totransmit.

In an example, the UPF may send to a base station, the data packet.

In an example, the first message may comprise an identifier of thewireless device, and/or the like.

In an example, the UPF may send to the base station, the data packet viaan intermediate UPF. The UPF may be a packet data unit session anchorUPF (PSA-UPF).

In an example, the AMF may send to a base station a context releasecommand The context release command message may comprise the AMF UE NGAPID IE, the RAN UE NGAP ID IE, and/or the like. The base station mayrelease signaling resources and user data resources associated with thewireless device. The base station may send to the AMF, a context releasecomplete message indicating a result of the context release command

In an example, the SMF may determine to send the release assistanceindicator to an AMF. In an example, the determining may be based on astatus of at least one packet data unit session associated with thewireless device.

In an example embodiment, a session management function (SMF) mayreceive from a user plane function (UPF), a first message. The firstmessage may comprise a release assistance indicator indicating end ofpacket transmission for a packet data unit session of a wireless device.The SMF may send, to the UPF a session modification request message. Thesession modification request message may indicate release of user planetunnel. The session modification request message may comprise theidentifier of a session between the SMF and the UPF, and/or the like.The SMF may send to an access and mobility management function (AMF), athird message. The third message may indicate release of a non-accessstratum connection associated with the wireless device. The thirdmessage may comprise the release assistance indicator, an identifier ofthe packet data unit session, and/or the like.

In an example embodiment, a session management function (SMF) mayreceive from a network exposure function (NEF), a first message. Thefirst message may comprise a release assistance indicator that mayindicate end of packet transmission for a packet data unit session of awireless device.

In an example, the SMF may send to a user plane function (UPF), asession modification request message. The session modification requestmessage may indicate release of user plane tunnel, (and/or tunnelinformation). The session modification request message may comprise theidentifier of a session between the SMF and the UPF.

In an example, the SMF may send to an access and mobility managementfunction (AMF), a third message indicating release of a non-accessstratum connection associated with the wireless device. The thirdmessage may comprise the release assistance indicator, an identifier ofthe packet data unit session, and/or the like.

In an example, the NEF may send to the UPF a data packet. In an example,the first message may comprise a data packet. In an example, the SMF mayreceive a data packet from the NEF. The SMF may send/forward the datapacket to the UPF via the session between the SMF and the UPF.

In an example, the UPF may send to a base station the data packet.

In an example, the AMF may send to a base station a context releasecommand message. The context release command message may comprise an AMFUE NGAP ID IE, a RAN UE NGAP ID IE, and/or the like.

In an example, the base station may release signaling resources and userdata resources associated with the wireless device. the base station maysend to the AMF, a context release complete message indicating a resultof the context release command

In an example, the SMF may determine to send the release assistanceindicator to an AMF. The determining may be based on a status of atleast one packet data unit session associated with the wireless device.The AMF may determine to release a non-access stratum connection of thewireless device. The may AMF determine to release the non-access stratumconnection of the wireless device based on pending data packets for atleast one packet data unit session of the wireless device.

In an example embodiment, a user plane function (UPF) may receive from anetwork exposure function (NEF), a first message comprising a releaseassistance indicator. The indicator may indicate end of packettransmission for a packet data unit session of a wireless device.

In an example, the UPF may send to a session management function (SMF),a second message. The second message may indicate a release request. Thesecond message may comprise an identifier of a session between the SMFand the UPF, the release assistance indicator, and/or the like. The UPFmay release based on the indication, a user plane tunnel of the packetdata unit session of the wireless device.

In an example, the SMF may send to an access and mobility managementfunction (AMF), a third message. The third message may comprise therelease assistance indicator, an identifier of the packet data unitsession, and/or the like.

In an example, the AMF may determine to release a non-access stratumconnection of the wireless device. The AMF may determine to release thenon-access stratum connection of the wireless device based on pendingdata packets for at least one packet data unit session of the wirelessdevice.

In an example, the release request may indicate deactivation of thepacket data unit session of the wireless device.

In an example, identifier of the session between the SMF and the UPF maybe an N4 session identifier of an N4 session.

In an example, the NEF may receive from an application function, afourth message. The fourth message may comprise the data packet, therelease assistance indicator, and/or the like.

In an example, the first message may comprise a data packet.

In an example, the UPF may determine based on the indication, that thedata packet is a last data packet for the packet data unit session totransmit. The UPF may send to a base station, the data packet.

According to various embodiments, a device such as, a SMF, a UPF, anNEF, a wireless device, a base station, and/or the like, may compriseone or more processors and memory. The memory may store instructionsthat, when executed by the one or more processors, cause the device toperform a series of actions. Embodiments of example actions areillustrated in the accompanying figures and specification. Features fromvarious embodiments may be combined to create yet further embodiments.

FIG. 37 is a flow diagram as per an aspect of an example embodiment ofthe present disclosure. At 3710, a session management function (SMF)receives a message from a network exposure function (NEF). The messagecomprises downlink data and a release assistance indicator (RAI). TheRAI indicates that transmission of uplink data by a wireless device isexpected subsequent to transmission of the downlink data. The RAIindicates a release of a connection associated with the wireless deviceafter the transmission of uplink data. At 3720, the SMF receives anindication that the uplink data is transmitted. At 3730, the SMF uponreceiving the indication, sends a release message to an access andmobility management function (AMF). The release message indicatesrelease of a non-access stratum message associated with the wirelessdevice. The release message comprises the release assistance indicator.

According to an example embodiment, the AMF may send to a base station acontext release command message. The context release command message maycomprise an AMF UE next generation application protocol identifierinformation element (NGAP ID IE), a radio access network (RAN) UE NGAPID IE, and/or the like. According to an example embodiment, the basestation may release signaling resources of the wireless device inresponse to the context release command message. According to an exampleembodiment, the base station may send to the AMF, a context releasecomplete message indicating a result of the context release commandmessage. According to an example embodiment, the sending of the releasemessage may be based on a status of a packet data unit sessionassociated with the wireless device. According to an example embodiment,the status of the Packet Data Unit (PDU) session may indicate that thePDU session is the last PDU session of the wireless device. According toan example embodiment, the AMF may determine to release the non-accessstratum connection of the wireless device. According to an exampleembodiment, the AMF may determine to release the non-access stratumconnection of the wireless device based on pending data packets for apacket data unit session of the wireless device. According to an exampleembodiment, the AMF may determine to release the non-access stratumconnection of the wireless device based on a status of a PDU session ofthe wireless device indicating whether the PDU session is the lastactive PDU session. According to an example embodiment, the SMF may sendto a user plane function, a session modification request message inresponse to receiving the RAI. According to an example embodiment, thesession modification request message may comprise an identifier of asession between the SMF and the User Plane Function. According to anexample embodiment, the session modification request message maycomprise an identifier of an indication to release an access networktunnel for the wireless device. According to an example embodiment, theSMF may send to the wireless device, the downlink data. According to anexample embodiment, the SMF may send the downlink data to the wirelessdevice via the AMF. According to an example embodiment, the SMF may sendthe downlink data to the wireless device via a user plane function.According to an example embodiment, the transmission of the uplink dataand the transmission of the downlink data may be part of the same PDUsession. According to an example embodiment, the indication that theuplink data is transmitted comprises the uplink data. According to anexample embodiment, the RAI may comprise a packet count parameterindicating a number of expected uplink data packets. According to anexample embodiment, the release message may comprises an identifier of apacket data unit session of the wireless device. According to an exampleembodiment, the RAI may comprise an information element. The informationelement may comprise an indication that no further transmission of theuplink data subsequent to a transmission of the downlink data isexpected. The information element may comprise an indication that atransmission of the uplink data subsequent to a transmission of thedownlink data is expected. According to an example embodiment, the RAImay comprise a packet count associated with the transmission of theuplink data. The RAI may comprise a time duration parameter indicating atime duration for which UL data is expected.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” or “one or more.” Similarly, any term thatends with the suffix “(s)” is to be interpreted as “at least one” or“one or more.” In this disclosure, the term “may” is to be interpretedas “may, for example.” In other words, the term “may” is indicative thatthe phrase following the term “may” is an example of one of a multitudeof suitable possibilities that may, or may not, be employed to one ormore of the various embodiments. If A and B are sets and every elementof A is also an element of B, A is called a subset of B. In thisspecification, only non-empty sets and subsets are considered. Forexample, possible subsets of B={cell1, cell2} are: {cell1}, {cell2}, and{cell1, cell2}. The phrase “based on” is indicative that the phrasefollowing the term “based on” is an example of one of a multitude ofsuitable possibilities that may, or may not, be employed to one or moreof the various embodiments. The phrase “in response to” is indicativethat the phrase following the phrase “in response to” is an example ofone of a multitude of suitable possibilities that may, or may not, beemployed to one or more of the various embodiments. The terms“including” and “comprising” should be interpreted as meaning“including, but not limited to.” In this disclosure, the abbreviation“e.g.” means “for example” and is followed by one or more examples thatillustrate a term receding the abbreviation.

In this disclosure and the claims, differentiating terms like “first,”“second,” “third,” identify separate elements without implying anordering of the elements or functionality of the elements.Differentiating terms may be replaced with other differentiating termswhen describing an embodiment.

In this disclosure, various embodiments are disclosed. Limitations,features, and/or elements from the disclosed example embodiments may becombined to create further embodiments within the scope of thedisclosure.

In this disclosure, parameters (Information elements: IEs) may compriseone or more objects, and each of those objects may comprise one or moreother objects. For example, if parameter (IE) N comprises parameter (IE)M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) Kcomprises parameter (information element) J, then, for example, Ncomprises K, and N comprises J. In an example embodiment, when one ormore messages comprise a plurality of parameters, it implies that aparameter in the plurality of parameters is in at least one of the oneor more messages, but does not have to be in each of the one or moremessages.

Furthermore, many features presented above are described as beingoptional through the use of “may” or the use of parentheses. For thesake of brevity and legibility, the present disclosure does notexplicitly recite each and every permutation that may be obtained bychoosing from the set of optional features. However, the presentdisclosure is to be interpreted as explicitly disclosing all suchpermutations. For example, a system described as having three optionalfeatures may be embodied in seven different ways, namely with just oneof the three possible features, with any two of the three possiblefeatures or with all three of the three possible features.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e. hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLabVIEWMathScript. Additionally, it may be possible to implement modulesusing physical hardware that incorporates discrete or programmableanalog, digital and/or quantum hardware. Examples of programmablehardware comprise: computers, microcontrollers, microprocessors,application-specific integrated circuits (ASICs); field programmablegate arrays (FPGAs); and complex programmable logic devices (CPLDs).Computers, microcontrollers and microprocessors are programmed usinglanguages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDsare often programmed using hardware description languages (HDL) such asVHSIC hardware description language (VHDL) or Verilog that configureconnections between internal hardware modules with lesser functionalityon a programmable device. Finally, it needs to be emphasized that theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the scope. In fact, after reading the abovedescription, it will be apparent to one skilled in the relevant art(s)how to implement alternative embodiments. Thus, the present embodimentsshould not be limited by any of the above described exemplaryembodiments. In particular, it should be noted that, for examplepurposes, the above explanation has focused on mission critical servicessuch as mission critical push-to-talk services employing media typessuch as audio services, video services and media services. However, oneskilled in the art will recognize that embodiments of the invention mayalso be implemented in a system comprising other types of services suchas, for example, data services, augmented reality services, data fusionservices, combinations thereof, and/or the like.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: receiving, by a sessionmanagement function (SMF) from a network exposure function (NEF), amessage comprising downlink data and a release assistance indicator(RAI), the RAI indicating: transmission of uplink data by a wirelessdevice is expected subsequent to transmission of the downlink data ; anda release of a connection associated with the wireless device after thetransmission of uplink data; receiving, by the SMF, an indication thatthe uplink data is transmitted; and sending, by the SMF to an access andmobility management function (AMF) based on receiving of the indication,a release message indicating release of a non-access stratum connectionassociated with the wireless device, the release message comprising therelease assistance indicator.
 2. The method of claim 1, wherein the AMFsends to a base station a context release command message comprising: anAMF UE next generation application protocol identifier informationelement (NGAP ID IE); and a radio access network (RAN) UE NGAP ID IE. 3.The method claim 2, wherein the base station releases signalingresources of the wireless device in response to the context releasecommand message.
 4. The method of claim 3, wherein the base stationsends to the AMF, a context release complete message indicating a resultof the context release command message.
 5. The method of claim 1,wherein the sending of the release message is based on a status of apacket data unit session associated with the wireless device.
 6. Themethod of claim 5, wherein the status of the Packet Data Unit (PDU)session indicates that the PDU session is the last PDU session of thewireless device.
 7. The method of claim 1, wherein the AMF determines torelease the non-access stratum connection of the wireless device.
 8. Themethod of claim 7, wherein the AMF determines to release the non-accessstratum connection of the wireless device based on pending data packetsfor a packet data unit session of the wireless device.
 9. The method ofclaim 7, wherein the AMF determines to release the non-access stratumconnection of the wireless device based on a status of a PDU session ofthe wireless device indicating whether the PDU session is the lastactive PDU session.
 10. The method of claim 1, further comprisingsending by the SMF to a user plane function, a session modificationrequest message in response to receiving the RAI.
 11. The method ofclaim 10, wherein the session modification request message comprises: anidentifier of a session between the SMF and the User Plane Function; andan indication to release an access network tunnel for the wirelessdevice.
 12. The method of claim 1, further comprising sending, by theSMF to the wireless device, the downlink data.
 13. The method of claim12, wherein the SMF sends the downlink data to the wireless device viathe AMF.
 14. The method of claim 12, wherein the SMF sends the downlinkdata to the wireless device via a user plane function.
 15. The method ofclaim 1, wherein the transmission of the uplink data and thetransmission of the downlink data are part of the same PDU session. 16.The method of claim 1, wherein the indication that the uplink data istransmitted comprises the uplink data.
 17. The method of claim 1,wherein the RAI further comprises a packet count parameter indicating anumber of expected uplink data packets.
 18. The method of claim 1,wherein the release message further comprises an identifier of a packetdata unit session of the wireless device.
 19. The method of claim 1,wherein the RAI comprises an information element comprising anindication that: no further transmission of the uplink data subsequentto a transmission of the downlink data is expected; or a transmission ofthe uplink data subsequent to a transmission of the downlink data isexpected.
 20. The method of claim 19, wherein the RAI further comprises:a packet count associated with the transmission of the uplink data; anda time duration parameter indicating a time duration for which UL datais expected.